replace usage of guava with standard java

Avoid adding extra third party dependency 'guava' by replacing methods with equivalent alternatives in standard jdk.

This helps users of etcd since every transitive third party dependency requires more code to be downloaded and might result in dependency conflicts.

fixes #1207

gradle/libs.versions.toml

@@ -3,7 +3,6 @@ grpc = "1.57.2"
 log4j = "2.20.0"
 mockito = "5.5.0"
 slf4j = "2.0.7"
-guava = "32.1.2-jre"
 assertj = "3.24.2"
 junit = "5.10.0"
 testcontainers = "1.19.0"
@@ -29,7 +28,6 @@ testRetryPlugin = "1.5.3"
 
 [libraries]
 slf4j = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
-guava = { module = "com.google.guava:guava", version.ref = "guava" }
 assertj = { module = "org.assertj:assertj-core", version.ref = "assertj" }
 junit = { module = "org.junit.jupiter:junit-jupiter", version.ref = "junit" }
 testcontainers = { module = "org.testcontainers:testcontainers", version.ref = "testcontainers" }

jetcd-common/build.gradle

@@ -17,7 +17,6 @@
 
 dependencies {
     api libs.slf4j
-    api libs.guava
     api libs.grpcCore
 
     testImplementation libs.bundles.testing

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/EtcdException.java

@@ -16,7 +16,7 @@
 
 package io.etcd.jetcd.common.exception;
 
-import static com.google.common.base.Preconditions.checkNotNull;
+import java.util.Objects;
 
 /**
  * Base exception type for all exceptions produced by the etcd service.
@@ -27,7 +27,7 @@ public class EtcdException extends RuntimeException {
 
     EtcdException(ErrorCode code, String message, Throwable cause) {
         super(message, cause);
-        this.code = checkNotNull(code);
+        this.code = Objects.requireNonNull(code, "Error code must not be null");
     }
 
     /**

jetcd-common/src/main/java/io/etcd/jetcd/common/exception/EtcdExceptionFactory.java

@@ -16,9 +16,10 @@
 
 package io.etcd.jetcd.common.exception;
 
+import java.util.Objects;
+
 import io.grpc.Status;
 
-import static com.google.common.base.Preconditions.checkNotNull;
 import static io.grpc.Status.fromThrowable;
 
 /**
@@ -65,7 +66,7 @@ public static EtcdException handleInterrupt(InterruptedException e) {
     }
 
     public static EtcdException toEtcdException(Throwable cause) {
-        checkNotNull(cause, "cause can't be null");
+        Objects.requireNonNull(cause, "cause can't be null");
         if (cause instanceof EtcdException) {
             return (EtcdException) cause;
         }
@@ -74,7 +75,7 @@ public static EtcdException toEtcdException(Throwable cause) {
     }
 
     public static EtcdException toEtcdException(Status status) {
-        checkNotNull(status, "status can't be null");
+        Objects.requireNonNull(status, "status can't be null");
         return fromStatus(status);
     }
 

jetcd-core/src/main/java/io/etcd/jetcd/ByteSequence.java

@@ -17,8 +17,8 @@
 package io.etcd.jetcd;
 
 import java.nio.charset.Charset;
+import java.util.Objects;
 
-import com.google.common.base.Preconditions;
 import com.google.protobuf.ByteString;
 
 /**
@@ -32,7 +32,7 @@ public final class ByteSequence {
     private final ByteString byteString;
 
     private ByteSequence(ByteString byteString) {
-        Preconditions.checkNotNull(byteString, "byteString should not be null");
+        Objects.requireNonNull(byteString, "byteString should not be null");
         this.byteString = byteString;
         this.hashVal = byteString.hashCode();
     }
@@ -58,7 +58,7 @@ public boolean startsWith(ByteSequence prefix) {
      * @return       a new {@code ByteSequence} instance
      */
     public ByteSequence concat(ByteSequence other) {
-        Preconditions.checkNotNull(other, "other byteSequence should not be null");
+        Objects.requireNonNull(other, "other byteSequence should not be null");
         return new ByteSequence(this.byteString.concat(other.byteString));
     }
 
@@ -69,7 +69,7 @@ public ByteSequence concat(ByteSequence other) {
      * @return       a new {@code ByteSequence} instance
      */
     public ByteSequence concat(ByteString other) {
-        Preconditions.checkNotNull(other, "other byteSequence should not be null");
+        Objects.requireNonNull(other, "other byteSequence should not be null");
         return new ByteSequence(this.byteString.concat(other));
     }
 

jetcd-core/src/main/java/io/etcd/jetcd/ClientBuilder.java

@@ -24,6 +24,7 @@
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
 
 import javax.net.ssl.SSLException;
 
@@ -37,9 +38,7 @@
 import io.netty.handler.ssl.SslContext;
 import io.netty.handler.ssl.SslContextBuilder;
 
-import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
-import com.google.common.collect.Streams;
 
 /**
  * ClientBuilder knows how to create a Client instance.
@@ -131,15 +130,15 @@ public ClientBuilder endpoints(URI... endpoints) {
      * @throws IllegalArgumentException if some endpoint is invalid
      */
     public ClientBuilder endpoints(Iterable<URI> endpoints) {
-        Preconditions.checkNotNull(endpoints, "endpoints can't be null");
+        Objects.requireNonNull(endpoints, "endpoints can't be null");
 
         endpoints.forEach(e -> {
             if (e.getHost() == null) {
                 throw new IllegalArgumentException("Unable to compute target from endpoint: '" + e + "'");
             }
         });
 
-        final String target = Streams.stream(endpoints)
+        final String target = StreamSupport.stream(endpoints.spliterator(), false)
             .map(e -> e.getHost() + (e.getPort() != -1 ? ":" + e.getPort() : ""))
             .distinct()
             .collect(Collectors.joining(","));
@@ -173,7 +172,7 @@ public ByteSequence user() {
      * @throws NullPointerException if user is <code>null</code>
      */
     public ClientBuilder user(ByteSequence user) {
-        Preconditions.checkNotNull(user, "user can't be null");
+        Objects.requireNonNull(user, "user can't be null");
         this.user = user;
         return this;
     }
@@ -195,7 +194,7 @@ public ByteSequence password() {
      * @throws NullPointerException if password is <code>null</code>
      */
     public ClientBuilder password(ByteSequence password) {
-        Preconditions.checkNotNull(password, "password can't be null");
+        Objects.requireNonNull(password, "password can't be null");
         this.password = password;
         return this;
     }
@@ -218,7 +217,7 @@ public ByteSequence namespace() {
      * @throws NullPointerException if namespace is <code>null</code>
      */
     public ClientBuilder namespace(ByteSequence namespace) {
-        Preconditions.checkNotNull(namespace, "namespace can't be null");
+        Objects.requireNonNull(namespace, "namespace can't be null");
         this.namespace = namespace;
         return this;
     }
@@ -240,7 +239,7 @@ public ExecutorService executorService() {
      * @throws NullPointerException if executorService is <code>null</code>
      */
     public ClientBuilder executorService(ExecutorService executorService) {
-        Preconditions.checkNotNull(executorService, "executorService can't be null");
+        Objects.requireNonNull(executorService, "executorService can't be null");
         this.executorService = executorService;
         return this;
     }
@@ -253,7 +252,7 @@ public ClientBuilder executorService(ExecutorService executorService) {
      * @throws NullPointerException if loadBalancerPolicy is <code>null</code>
      */
     public ClientBuilder loadBalancerPolicy(String loadBalancerPolicy) {
-        Preconditions.checkNotNull(loadBalancerPolicy, "loadBalancerPolicy can't be null");
+        Objects.requireNonNull(loadBalancerPolicy, "loadBalancerPolicy can't be null");
         this.loadBalancerPolicy = loadBalancerPolicy;
         return this;
     }

jetcd-core/src/main/java/io/etcd/jetcd/Preconditions.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2016-2023 The jetcd authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.etcd.jetcd;
+
+public class Preconditions {
+
+    public static void checkArgument(boolean expression, String errorMessage) {
+        if (!expression) {
+            throw new IllegalArgumentException(errorMessage);
+        }
+    }
+
+    public static void checkState(boolean expression, String errorMessage) {
+        if (!expression) {
+            throw new IllegalStateException(errorMessage);
+        }
+    }
+}

jetcd-core/src/main/java/io/etcd/jetcd/impl/AuthCredential.java

@@ -31,7 +31,7 @@
 
 import com.google.protobuf.ByteString;
 
-import static com.google.common.base.Preconditions.checkArgument;
+import static io.etcd.jetcd.Preconditions.checkArgument;
 
 /**
  * AuthTokenInterceptor fills header with Auth token of any rpc calls and

jetcd-core/src/main/java/io/etcd/jetcd/impl/AuthImpl.java

@@ -55,7 +55,7 @@
 
 import com.google.protobuf.ByteString;
 
-import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 /**
  * Implementation of etcd auth client.
@@ -88,8 +88,8 @@ public CompletableFuture<AuthDisableResponse> authDisable() {
 
     @Override
     public CompletableFuture<AuthUserAddResponse> userAdd(ByteSequence user, ByteSequence password) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(password, "password can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(password, "password can't be null");
 
         AuthUserAddRequest addRequest = AuthUserAddRequest.newBuilder()
             .setNameBytes(ByteString.copyFrom(user.getBytes()))
@@ -103,7 +103,7 @@ public CompletableFuture<AuthUserAddResponse> userAdd(ByteSequence user, ByteSeq
 
     @Override
     public CompletableFuture<AuthUserDeleteResponse> userDelete(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        requireNonNull(user, "user can't be null");
 
         AuthUserDeleteRequest deleteRequest = AuthUserDeleteRequest.newBuilder()
             .setNameBytes(ByteString.copyFrom(user.getBytes()))
@@ -116,8 +116,8 @@ public CompletableFuture<AuthUserDeleteResponse> userDelete(ByteSequence user) {
 
     @Override
     public CompletableFuture<AuthUserChangePasswordResponse> userChangePassword(ByteSequence user, ByteSequence password) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(password, "password can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(password, "password can't be null");
 
         AuthUserChangePasswordRequest changePasswordRequest = AuthUserChangePasswordRequest.newBuilder()
             .setNameBytes(ByteString.copyFrom(user.getBytes()))
@@ -131,7 +131,7 @@ public CompletableFuture<AuthUserChangePasswordResponse> userChangePassword(Byte
 
     @Override
     public CompletableFuture<AuthUserGetResponse> userGet(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        requireNonNull(user, "user can't be null");
 
         AuthUserGetRequest userGetRequest = AuthUserGetRequest.newBuilder()
             .setNameBytes(ByteString.copyFrom(user.getBytes()))
@@ -153,8 +153,8 @@ public CompletableFuture<AuthUserListResponse> userList() {
 
     @Override
     public CompletableFuture<AuthUserGrantRoleResponse> userGrantRole(ByteSequence user, ByteSequence role) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(role, "key can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(role, "key can't be null");
 
         AuthUserGrantRoleRequest userGrantRoleRequest = AuthUserGrantRoleRequest.newBuilder()
             .setUserBytes(ByteString.copyFrom(user.getBytes()))
@@ -168,8 +168,8 @@ public CompletableFuture<AuthUserGrantRoleResponse> userGrantRole(ByteSequence u
 
     @Override
     public CompletableFuture<AuthUserRevokeRoleResponse> userRevokeRole(ByteSequence user, ByteSequence role) {
-        checkNotNull(user, "user can't be null");
-        checkNotNull(role, "key can't be null");
+        requireNonNull(user, "user can't be null");
+        requireNonNull(role, "key can't be null");
 
         AuthUserRevokeRoleRequest userRevokeRoleRequest = AuthUserRevokeRoleRequest.newBuilder()
             .setNameBytes(ByteString.copyFrom(user.getBytes()))
@@ -183,7 +183,7 @@ public CompletableFuture<AuthUserRevokeRoleResponse> userRevokeRole(ByteSequence
 
     @Override
     public CompletableFuture<AuthRoleAddResponse> roleAdd(ByteSequence user) {
-        checkNotNull(user, "user can't be null");
+        requireNonNull(user, "user can't be null");
 
         AuthRoleAddRequest roleAddRequest = AuthRoleAddRequest.newBuilder().setNameBytes(ByteString.copyFrom(user.getBytes()))
             .build();
@@ -196,10 +196,10 @@ public CompletableFuture<AuthRoleAddResponse> roleAdd(ByteSequence user) {
     @Override
     public CompletableFuture<AuthRoleGrantPermissionResponse> roleGrantPermission(ByteSequence role, ByteSequence key,
         ByteSequence rangeEnd, Permission.Type permType) {
-        checkNotNull(role, "role can't be null");
-        checkNotNull(key, "key can't be null");
-        checkNotNull(rangeEnd, "rangeEnd can't be null");
-        checkNotNull(permType, "permType can't be null");
+        requireNonNull(role, "role can't be null");
+        requireNonNull(key, "key can't be null");
+        requireNonNull(rangeEnd, "rangeEnd can't be null");
+        requireNonNull(permType, "permType can't be null");
 
         io.etcd.jetcd.api.Permission.Type type;
         switch (permType) {
@@ -235,7 +235,7 @@ public CompletableFuture<AuthRoleGrantPermissionResponse> roleGrantPermission(By
 
     @Override
     public CompletableFuture<AuthRoleGetResponse> roleGet(ByteSequence role) {
-        checkNotNull(role, "role can't be null");
+        requireNonNull(role, "role can't be null");
 
         AuthRoleGetRequest roleGetRequest = AuthRoleGetRequest.newBuilder()
             .setRoleBytes(ByteString.copyFrom(role.getBytes()))
@@ -258,9 +258,9 @@ public CompletableFuture<AuthRoleListResponse> roleList() {
     @Override
     public CompletableFuture<AuthRoleRevokePermissionResponse> roleRevokePermission(ByteSequence role, ByteSequence key,
         ByteSequence rangeEnd) {
-        checkNotNull(role, "role can't be null");
-        checkNotNull(key, "key can't be null");
-        checkNotNull(rangeEnd, "rangeEnd can't be null");
+        requireNonNull(role, "role can't be null");
+        requireNonNull(key, "key can't be null");
+        requireNonNull(rangeEnd, "rangeEnd can't be null");
 
         AuthRoleRevokePermissionRequest roleRevokePermissionRequest = AuthRoleRevokePermissionRequest.newBuilder()
             .setRoleBytes(ByteString.copyFrom(role.getBytes()))
@@ -275,7 +275,7 @@ public CompletableFuture<AuthRoleRevokePermissionResponse> roleRevokePermission(
 
     @Override
     public CompletableFuture<AuthRoleDeleteResponse> roleDelete(ByteSequence role) {
-        checkNotNull(role, "role can't be null");
+        requireNonNull(role, "role can't be null");
         AuthRoleDeleteRequest roleDeleteRequest = AuthRoleDeleteRequest.newBuilder()
             .setRoleBytes(ByteString.copyFrom(role.getBytes()))
             .build();