diff --git a/src/main/java/org/proshin/finapi/accesstoken/FpAccessTokens.java b/src/main/java/org/proshin/finapi/accesstoken/FpAccessTokens.java
index 4f94ff1..ebc73b9 100644
--- a/src/main/java/org/proshin/finapi/accesstoken/FpAccessTokens.java
+++ b/src/main/java/org/proshin/finapi/accesstoken/FpAccessTokens.java
@@ -15,7 +15,6 @@
  */
 package org.proshin.finapi.accesstoken;
 
-import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 import org.apache.http.HttpStatus;
@@ -57,7 +56,7 @@ public AccessToken clientToken(final String clientId, final String clientSecret)
                         ).get(),
                     new StringEntity(
                         "",
-                        ContentType.create("application/json", StandardCharsets.UTF_8)
+                        ContentType.APPLICATION_JSON
                     ),
                     HttpStatus.SC_OK
                 )
@@ -85,7 +84,7 @@ public AccessToken userToken(
                         ).get(),
                     new StringEntity(
                         "",
-                        ContentType.create("application/json", StandardCharsets.UTF_8)
+                        ContentType.APPLICATION_JSON
                     ),
                     HttpStatus.SC_OK
                 )
@@ -107,7 +106,7 @@ public AccessToken userToken(final String clientId, final String clientSecret, f
                         ).get(),
                     new StringEntity(
                         "",
-                        ContentType.create("application/json", StandardCharsets.UTF_8)
+                        ContentType.APPLICATION_JSON
                     ),
                     HttpStatus.SC_OK
                 )
@@ -145,7 +144,7 @@ public void revoke(final AccessToken clientToken, final AccessToken userToken, f
             clientToken,
             new StringEntity(
                 "",
-                ContentType.create("application/json", StandardCharsets.UTF_8)
+                ContentType.APPLICATION_JSON
             ),
             HttpStatus.SC_OK
         );
diff --git a/src/main/java/org/proshin/finapi/account/Type.java b/src/main/java/org/proshin/finapi/account/Type.java
index d86cbd9..ae59307 100644
--- a/src/main/java/org/proshin/finapi/account/Type.java
+++ b/src/main/java/org/proshin/finapi/account/Type.java
@@ -66,7 +66,7 @@ public TypeOf(final int code) {
         }
 
         public Type get() {
-            for (final Type type : Type.values()) {
+            for (final Type type : values()) {
                 if (type.asCode() == this.code) {
                     return type;
                 }
diff --git a/src/main/java/org/proshin/finapi/account/in/DailyBalancesCriteria.java b/src/main/java/org/proshin/finapi/account/in/DailyBalancesCriteria.java
index cedf139..a8e7e95 100644
--- a/src/main/java/org/proshin/finapi/account/in/DailyBalancesCriteria.java
+++ b/src/main/java/org/proshin/finapi/account/in/DailyBalancesCriteria.java
@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.StringOf;
 import org.proshin.finapi.primitives.pair.CommaSeparatedPair;
@@ -69,6 +70,7 @@ public DailyBalancesCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/account/in/FpQueryCriteria.java b/src/main/java/org/proshin/finapi/account/in/FpQueryCriteria.java
index 2132585..b1c3880 100644
--- a/src/main/java/org/proshin/finapi/account/in/FpQueryCriteria.java
+++ b/src/main/java/org/proshin/finapi/account/in/FpQueryCriteria.java
@@ -22,6 +22,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.stream.Collectors;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.account.Type;
 import org.proshin.finapi.primitives.StringOf;
@@ -99,6 +100,7 @@ public FpQueryCriteria withMaxBalance(final BigDecimal maxBalance) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/bank/in/BanksCriteria.java b/src/main/java/org/proshin/finapi/bank/in/BanksCriteria.java
index a972dee..6aaea32 100644
--- a/src/main/java/org/proshin/finapi/bank/in/BanksCriteria.java
+++ b/src/main/java/org/proshin/finapi/bank/in/BanksCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.bank.Bank;
 import org.proshin.finapi.primitives.BankingInterface;
@@ -106,6 +107,7 @@ public BanksCriteria withPaging(final PagingCriteria paging) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/bankconnection/BankConnection.java b/src/main/java/org/proshin/finapi/bankconnection/BankConnection.java
index 30774be..b17a567 100644
--- a/src/main/java/org/proshin/finapi/bankconnection/BankConnection.java
+++ b/src/main/java/org/proshin/finapi/bankconnection/BankConnection.java
@@ -76,6 +76,9 @@ public interface BankConnection {
     @Deprecated
     boolean ibanOnlyDirectDebitSupported();
 
+    /**
+     * @deprecated since v0.1.92 due to PSD2-related changes
+     */
     @Deprecated
     boolean collectiveMoneyTransferSupported();
 
diff --git a/src/main/java/org/proshin/finapi/bankconnection/FpBankConnection.java b/src/main/java/org/proshin/finapi/bankconnection/FpBankConnection.java
index 8df6ae8..b715991 100644
--- a/src/main/java/org/proshin/finapi/bankconnection/FpBankConnection.java
+++ b/src/main/java/org/proshin/finapi/bankconnection/FpBankConnection.java
@@ -118,7 +118,6 @@ public boolean ibanOnlyDirectDebitSupported() {
     }
 
     @Override
-    @Deprecated
     public boolean collectiveMoneyTransferSupported() {
         return this.origin.getBoolean("collectiveMoneyTransferSupported");
     }
diff --git a/src/main/java/org/proshin/finapi/category/FpCategories.java b/src/main/java/org/proshin/finapi/category/FpCategories.java
index cf412f6..a685823 100644
--- a/src/main/java/org/proshin/finapi/category/FpCategories.java
+++ b/src/main/java/org/proshin/finapi/category/FpCategories.java
@@ -15,6 +15,7 @@
  */
 package org.proshin.finapi.category;
 
+import org.apache.http.HttpStatus;
 import org.json.JSONArray;
 import org.json.JSONObject;
 import org.proshin.finapi.accesstoken.AccessToken;
@@ -88,7 +89,7 @@ public Category create(final CreateCategoryParameters parameters) {
         return new FpCategory(
             this.endpoint,
             this.token,
-            new JSONObject(this.endpoint.post(this.url, this.token, parameters, 201)),
+            new JSONObject(this.endpoint.post(this.url, this.token, parameters, HttpStatus.SC_CREATED)),
             this.url
         );
     }
diff --git a/src/main/java/org/proshin/finapi/category/in/CashFlowsCriteria.java b/src/main/java/org/proshin/finapi/category/in/CashFlowsCriteria.java
index c31ed3e..df2be0d 100644
--- a/src/main/java/org/proshin/finapi/category/in/CashFlowsCriteria.java
+++ b/src/main/java/org/proshin/finapi/category/in/CashFlowsCriteria.java
@@ -20,6 +20,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.Direction;
 import org.proshin.finapi.primitives.StringOf;
@@ -130,6 +131,7 @@ public CashFlowsCriteria withOrdering(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/category/in/CategoriesCriteria.java b/src/main/java/org/proshin/finapi/category/in/CategoriesCriteria.java
index 5cfcc7e..6205f17 100644
--- a/src/main/java/org/proshin/finapi/category/in/CategoriesCriteria.java
+++ b/src/main/java/org/proshin/finapi/category/in/CategoriesCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.CommaSeparatedPair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
@@ -62,6 +63,7 @@ public CategoriesCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/client/out/FpConfiguration.java b/src/main/java/org/proshin/finapi/client/out/FpConfiguration.java
index abd7a67..6cc7a0e 100644
--- a/src/main/java/org/proshin/finapi/client/out/FpConfiguration.java
+++ b/src/main/java/org/proshin/finapi/client/out/FpConfiguration.java
@@ -81,7 +81,6 @@ public boolean isWebScrapingEnabled() {
     }
 
     @Override
-    @Deprecated
     public boolean isXs2aEnabled() {
         return this.origin.getBoolean("isXs2aEnabled");
     }
@@ -125,7 +124,6 @@ public boolean paymentsEnabled() {
     }
 
     @Override
-    @Deprecated
     public boolean pinStorageAvailableInWebForm() {
         return this.origin.getBoolean("pinStorageAvailableInWebForm");
     }
diff --git a/src/main/java/org/proshin/finapi/endpoint/Endpoint.java b/src/main/java/org/proshin/finapi/endpoint/Endpoint.java
index 52015c1..2089f22 100644
--- a/src/main/java/org/proshin/finapi/endpoint/Endpoint.java
+++ b/src/main/java/org/proshin/finapi/endpoint/Endpoint.java
@@ -15,7 +15,6 @@
  */
 package org.proshin.finapi.endpoint;
 
-import java.nio.charset.StandardCharsets;
 import org.apache.http.HttpEntity;
 import org.apache.http.HttpStatus;
 import org.apache.http.NameValuePair;
@@ -56,7 +55,7 @@ default String post(final String path, final AccessToken token, final Jsonable b
             token,
             new StringEntity(
                 body.asString(),
-                ContentType.create("application/json", StandardCharsets.UTF_8)
+                ContentType.APPLICATION_JSON
             ),
             HttpStatus.SC_OK
         );
@@ -68,7 +67,7 @@ default String post(final String path, final AccessToken token, final Jsonable b
             token,
             new StringEntity(
                 body.asString(),
-                ContentType.create("application/json", StandardCharsets.UTF_8)
+                ContentType.APPLICATION_JSON
             ),
             expected
         );
diff --git a/src/main/java/org/proshin/finapi/endpoint/FpEndpoint.java b/src/main/java/org/proshin/finapi/endpoint/FpEndpoint.java
index 94b04bd..e41bac9 100644
--- a/src/main/java/org/proshin/finapi/endpoint/FpEndpoint.java
+++ b/src/main/java/org/proshin/finapi/endpoint/FpEndpoint.java
@@ -71,8 +71,8 @@ public String get(final String path, final AccessToken token, final Iterable<Nam
             final HttpUriRequest get = new HttpGet(builder.build());
             get.addHeader(new AuthorizationHeader(token.accessToken()));
             final HttpResponse response = this.client.execute(get);
-            if (response.getStatusLine().getStatusCode() != 200) {
-                throw new FinapiException(200, response);
+            if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
+                throw new FinapiException(HttpStatus.SC_OK, response);
             }
             final String responseBody = new TextOf(
                 new InputOf(response.getEntity().getContent()),
@@ -101,8 +101,8 @@ public String delete(final String path, final AccessToken token, final Iterable<
             final HttpUriRequest delete = new HttpDelete(builder.build());
             delete.addHeader(new AuthorizationHeader(token.accessToken()));
             final HttpResponse response = this.client.execute(delete);
-            if (response.getStatusLine().getStatusCode() != 200) {
-                throw new FinapiException(200, response);
+            if (response.getStatusLine().getStatusCode() != HttpStatus.SC_OK) {
+                throw new FinapiException(HttpStatus.SC_OK, response);
             }
             final String responseBody = new TextOf(
                 new InputOf(response.getEntity().getContent()),
@@ -250,7 +250,7 @@ public String patch(final String path, final AccessToken token, final Jsonable b
             path, token,
             new StringEntity(
                 body.asString(),
-                ContentType.create("application/json", StandardCharsets.UTF_8)
+                ContentType.APPLICATION_JSON
             ),
             HttpStatus.SC_OK
         );
diff --git a/src/main/java/org/proshin/finapi/exception/NoFieldException.java b/src/main/java/org/proshin/finapi/exception/NoFieldException.java
index cb6eeb9..d97e10c 100644
--- a/src/main/java/org/proshin/finapi/exception/NoFieldException.java
+++ b/src/main/java/org/proshin/finapi/exception/NoFieldException.java
@@ -16,6 +16,8 @@
 package org.proshin.finapi.exception;
 
 public final class NoFieldException extends RuntimeException {
+    private static final long serialVersionUID = 260448112051805868L;
+
     public NoFieldException(final String message) {
         super(message);
     }
diff --git a/src/main/java/org/proshin/finapi/label/in/LabelsCriteria.java b/src/main/java/org/proshin/finapi/label/in/LabelsCriteria.java
index 1dc7eb3..da0f3f8 100644
--- a/src/main/java/org/proshin/finapi/label/in/LabelsCriteria.java
+++ b/src/main/java/org/proshin/finapi/label/in/LabelsCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.CommaSeparatedPair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
@@ -57,6 +58,7 @@ public LabelsCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/mandator/in/UsersCriteria.java b/src/main/java/org/proshin/finapi/mandator/in/UsersCriteria.java
index 1b21e24..1077b48 100644
--- a/src/main/java/org/proshin/finapi/mandator/in/UsersCriteria.java
+++ b/src/main/java/org/proshin/finapi/mandator/in/UsersCriteria.java
@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.StringOf;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
@@ -119,6 +120,7 @@ public UsersCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/notificationrule/FpNotificationRules.java b/src/main/java/org/proshin/finapi/notificationrule/FpNotificationRules.java
index 00f18b7..07660c9 100644
--- a/src/main/java/org/proshin/finapi/notificationrule/FpNotificationRules.java
+++ b/src/main/java/org/proshin/finapi/notificationrule/FpNotificationRules.java
@@ -15,6 +15,7 @@
  */
 package org.proshin.finapi.notificationrule;
 
+import org.apache.http.HttpStatus;
 import org.json.JSONArray;
 import org.json.JSONObject;
 import org.proshin.finapi.accesstoken.AccessToken;
@@ -72,7 +73,7 @@ public NotificationRule create(final CreatingParameters parameters) {
             this.endpoint,
             this.token,
             new JSONObject(
-                this.endpoint.post(this.url, this.token, parameters, 201)
+                this.endpoint.post(this.url, this.token, parameters, HttpStatus.SC_CREATED)
             ),
             this.url
         );
diff --git a/src/main/java/org/proshin/finapi/notificationrule/in/NotificationRulesCriteria.java b/src/main/java/org/proshin/finapi/notificationrule/in/NotificationRulesCriteria.java
index 7c44c0d..5c3a562 100644
--- a/src/main/java/org/proshin/finapi/notificationrule/in/NotificationRulesCriteria.java
+++ b/src/main/java/org/proshin/finapi/notificationrule/in/NotificationRulesCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.notificationrule.TriggerEvent;
 import org.proshin.finapi.primitives.pair.CommaSeparatedPair;
@@ -50,6 +51,7 @@ public NotificationRulesCriteria withDetails(final boolean includeDetails) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/payment/in/FpQueryCriteria.java b/src/main/java/org/proshin/finapi/payment/in/FpQueryCriteria.java
index 47ffc14..866e1ac 100644
--- a/src/main/java/org/proshin/finapi/payment/in/FpQueryCriteria.java
+++ b/src/main/java/org/proshin/finapi/payment/in/FpQueryCriteria.java
@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.StringOf;
 import org.proshin.finapi.primitives.pair.CommaSeparatedPair;
@@ -69,6 +70,7 @@ public FpQueryCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/primitives/StringOf.java b/src/main/java/org/proshin/finapi/primitives/StringOf.java
index 4275726..9261ec3 100644
--- a/src/main/java/org/proshin/finapi/primitives/StringOf.java
+++ b/src/main/java/org/proshin/finapi/primitives/StringOf.java
@@ -38,7 +38,7 @@ public StringOf(final TemporalAccessor value) {
 
     public StringOf(final BigDecimal value) {
         this(((Supplier<String>) () -> {
-            DecimalFormat df = (DecimalFormat) NumberFormat.getNumberInstance(Locale.ENGLISH);
+            final DecimalFormat df = (DecimalFormat) NumberFormat.getNumberInstance(Locale.ENGLISH);
             df.applyPattern("###.##");
             return df.format(value);
         }
diff --git a/src/main/java/org/proshin/finapi/primitives/paging/PagingCriteria.java b/src/main/java/org/proshin/finapi/primitives/paging/PagingCriteria.java
index 585ae89..5e67758 100644
--- a/src/main/java/org/proshin/finapi/primitives/paging/PagingCriteria.java
+++ b/src/main/java/org/proshin/finapi/primitives/paging/PagingCriteria.java
@@ -19,6 +19,7 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.function.Supplier;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
 
@@ -43,6 +44,7 @@ public PagingCriteria(final Supplier<? extends Iterator<NameValuePair>> origin)
         this.origin = origin;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.origin.get();
diff --git a/src/main/java/org/proshin/finapi/primitives/pair/UrlEncodedPair.java b/src/main/java/org/proshin/finapi/primitives/pair/UrlEncodedPair.java
index 39cd97c..8ee8879 100644
--- a/src/main/java/org/proshin/finapi/primitives/pair/UrlEncodedPair.java
+++ b/src/main/java/org/proshin/finapi/primitives/pair/UrlEncodedPair.java
@@ -46,7 +46,7 @@ public String getName() {
     public String getValue() {
         try {
             return URLEncoder.encode(this.origin.getValue(), StandardCharsets.UTF_8.displayName());
-        } catch (UnsupportedEncodingException e) {
+        } catch (final UnsupportedEncodingException e) {
             throw new RuntimeException(e);
         }
     }
diff --git a/src/main/java/org/proshin/finapi/security/in/SecuritiesCriteria.java b/src/main/java/org/proshin/finapi/security/in/SecuritiesCriteria.java
index 7f6c53e..b160207 100644
--- a/src/main/java/org/proshin/finapi/security/in/SecuritiesCriteria.java
+++ b/src/main/java/org/proshin/finapi/security/in/SecuritiesCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.CommaSeparatedPair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
@@ -62,6 +63,7 @@ public SecuritiesCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/tppcertificate/in/QueryTppCertificatesCriteria.java b/src/main/java/org/proshin/finapi/tppcertificate/in/QueryTppCertificatesCriteria.java
index 833216f..6c4375a 100644
--- a/src/main/java/org/proshin/finapi/tppcertificate/in/QueryTppCertificatesCriteria.java
+++ b/src/main/java/org/proshin/finapi/tppcertificate/in/QueryTppCertificatesCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
 
@@ -39,6 +40,7 @@ public QueryTppCertificatesCriteria withPage(final int page, final int perPage)
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppAuthenticationGroupsCriteria.java b/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppAuthenticationGroupsCriteria.java
index 8e2ef11..63d0a8c 100644
--- a/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppAuthenticationGroupsCriteria.java
+++ b/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppAuthenticationGroupsCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
 
@@ -54,6 +55,7 @@ public QueryTppAuthenticationGroupsCriteria withPage(final int page, final int p
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppCredentialsCriteria.java b/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppCredentialsCriteria.java
index b868c1c..bd1478d 100644
--- a/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppCredentialsCriteria.java
+++ b/src/main/java/org/proshin/finapi/tppcredential/in/QueryTppCredentialsCriteria.java
@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
 
@@ -44,6 +45,7 @@ public QueryTppCredentialsCriteria withPage(final int page, final int perPage) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/transaction/FpTransaction.java b/src/main/java/org/proshin/finapi/transaction/FpTransaction.java
index b095678..d530ced 100644
--- a/src/main/java/org/proshin/finapi/transaction/FpTransaction.java
+++ b/src/main/java/org/proshin/finapi/transaction/FpTransaction.java
@@ -159,7 +159,6 @@ public Iterable<Long> children() {
     }
 
     @Override
-    @Deprecated
     public Optional<PayPalData> payPalData() {
         return new OptionalObjectOf(this.origin, "paypalData").get()
             .map(FpPayPalData::new);
diff --git a/src/main/java/org/proshin/finapi/transaction/in/DeleteTransactionsCriteria.java b/src/main/java/org/proshin/finapi/transaction/in/DeleteTransactionsCriteria.java
index 76eb56f..48741c2 100644
--- a/src/main/java/org/proshin/finapi/transaction/in/DeleteTransactionsCriteria.java
+++ b/src/main/java/org/proshin/finapi/transaction/in/DeleteTransactionsCriteria.java
@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.StringOf;
 import org.proshin.finapi.primitives.pair.UrlEncodedPair;
@@ -49,6 +50,7 @@ public DeleteTransactionsCriteria withRememberingDeletion() {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/main/java/org/proshin/finapi/transaction/in/TransactionsCriteria.java b/src/main/java/org/proshin/finapi/transaction/in/TransactionsCriteria.java
index ac9fb15..fe51246 100644
--- a/src/main/java/org/proshin/finapi/transaction/in/TransactionsCriteria.java
+++ b/src/main/java/org/proshin/finapi/transaction/in/TransactionsCriteria.java
@@ -20,6 +20,7 @@
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.Nonnull;
 import org.apache.http.NameValuePair;
 import org.proshin.finapi.primitives.Direction;
 import org.proshin.finapi.primitives.StringOf;
@@ -157,6 +158,7 @@ public TransactionsCriteria orderBy(final String... orders) {
         return this;
     }
 
+    @Nonnull
     @Override
     public Iterator<NameValuePair> iterator() {
         return this.pairs.iterator();
diff --git a/src/test/java/org/proshin/finapi/bank/FpBankTest.java b/src/test/java/org/proshin/finapi/bank/FpBankTest.java
index 0caf5ce..4205129 100644
--- a/src/test/java/org/proshin/finapi/bank/FpBankTest.java
+++ b/src/test/java/org/proshin/finapi/bank/FpBankTest.java
@@ -32,7 +32,7 @@ public class FpBankTest {
 
     @Test
     public void test() {
-        final FpBank bank = new FpBank(
+        final Bank bank = new FpBank(
             new JSONObject('{' +
                 "  \"id\": 277672," +
                 "  \"name\": \"FinAPI Test Bank\"," +
diff --git a/src/test/java/org/proshin/finapi/bankconnection/FpBankConnectionTest.java b/src/test/java/org/proshin/finapi/bankconnection/FpBankConnectionTest.java
index fcaf9e7..7d6c3a5 100644
--- a/src/test/java/org/proshin/finapi/bankconnection/FpBankConnectionTest.java
+++ b/src/test/java/org/proshin/finapi/bankconnection/FpBankConnectionTest.java
@@ -36,7 +36,7 @@ public class FpBankConnectionTest extends TestWithMockedEndpoint {
 
     @Test
     public void testParsingJsonStructure() {
-        final FpBankConnection connection = new FpBankConnection(
+        final BankConnection connection = new FpBankConnection(
             this.endpoint(),
             new FakeAccessToken("user-token"),
             new JSONObject('{' +
@@ -138,7 +138,6 @@ public void testParsingJsonStructure() {
 
         assertThat(connection.ibanOnlyDirectDebitSupported()).isTrue();
         assertThat(connection.ibanOnlyMoneyTransferSupported()).isTrue();
-        //noinspection deprecation
         assertThat(connection.collectiveMoneyTransferSupported()).isTrue();
 
         assertThat(connection.accounts()).containsExactlyInAnyOrder(1L, 2L, 3L);
diff --git a/src/test/java/org/proshin/finapi/category/FpCategoryTest.java b/src/test/java/org/proshin/finapi/category/FpCategoryTest.java
index 543b5ee..a9b1711 100644
--- a/src/test/java/org/proshin/finapi/category/FpCategoryTest.java
+++ b/src/test/java/org/proshin/finapi/category/FpCategoryTest.java
@@ -31,7 +31,7 @@ public class FpCategoryTest extends TestWithMockedEndpoint {
 
     @Test
     public void test() {
-        final FpCategory category = new FpCategory(
+        final Category category = new FpCategory(
             this.endpoint(),
             new FakeAccessToken("test-user"),
             new JSONObject('{' +
diff --git a/src/test/java/org/proshin/finapi/mandator/out/FpDeletionResultTest.java b/src/test/java/org/proshin/finapi/mandator/out/FpDeletionResultTest.java
index 07f59ad..5b3d824 100644
--- a/src/test/java/org/proshin/finapi/mandator/out/FpDeletionResultTest.java
+++ b/src/test/java/org/proshin/finapi/mandator/out/FpDeletionResultTest.java
@@ -22,7 +22,7 @@
 public class FpDeletionResultTest {
     @Test
     public void test() {
-        final FpDeletionResult result = new FpDeletionResult(
+        final DeletionResult result = new FpDeletionResult(
             new JSONObject('{' +
                 "  \"deletedUsers\": [" +
                 "    \"first_user\"," +
diff --git a/src/test/java/org/proshin/finapi/notificationrule/FpNotificationRuleTest.java b/src/test/java/org/proshin/finapi/notificationrule/FpNotificationRuleTest.java
index 6e87304..d136e83 100644
--- a/src/test/java/org/proshin/finapi/notificationrule/FpNotificationRuleTest.java
+++ b/src/test/java/org/proshin/finapi/notificationrule/FpNotificationRuleTest.java
@@ -31,7 +31,7 @@ public class FpNotificationRuleTest extends TestWithMockedEndpoint {
 
     @Test
     public void testWithParams() {
-        final FpNotificationRule rule = new FpNotificationRule(
+        final NotificationRule rule = new FpNotificationRule(
             this.endpoint(),
             new FakeAccessToken("user-token"),
             new JSONObject('{' +
@@ -54,7 +54,7 @@ public void testWithParams() {
 
     @Test
     public void testWithoutParams() {
-        final FpNotificationRule rule = new FpNotificationRule(
+        final NotificationRule rule = new FpNotificationRule(
             this.endpoint(),
             new FakeAccessToken("user-token"),
             new JSONObject('{' +
diff --git a/src/test/java/org/proshin/finapi/primitives/paging/FpPagingTest.java b/src/test/java/org/proshin/finapi/primitives/paging/FpPagingTest.java
index 36d2f33..6e528b4 100644
--- a/src/test/java/org/proshin/finapi/primitives/paging/FpPagingTest.java
+++ b/src/test/java/org/proshin/finapi/primitives/paging/FpPagingTest.java
@@ -22,7 +22,7 @@
 public class FpPagingTest {
     @Test
     public void test() {
-        final FpPaging paging = new FpPaging(
+        final Paging paging = new FpPaging(
             new JSONObject('{' +
                 "  \"page\": 1," +
                 "  \"perPage\": 20," +
diff --git a/src/test/java/org/proshin/finapi/security/FpSecurityTest.java b/src/test/java/org/proshin/finapi/security/FpSecurityTest.java
index 2e79b47..fe025b6 100644
--- a/src/test/java/org/proshin/finapi/security/FpSecurityTest.java
+++ b/src/test/java/org/proshin/finapi/security/FpSecurityTest.java
@@ -28,7 +28,7 @@ public class FpSecurityTest {
 
     @Test
     public void test() {
-        final FpSecurity security = new FpSecurity(
+        final Security security = new FpSecurity(
             new JSONObject('{' +
                 "  \"id\": 1," +
                 "  \"accountId\": 2," +