diff --git a/src/main/java/org/apache/commons/beanutils/ConstructorUtils.java b/src/main/java/org/apache/commons/beanutils/ConstructorUtils.java
index 04849911f..663fdf571 100644
--- a/src/main/java/org/apache/commons/beanutils/ConstructorUtils.java
+++ b/src/main/java/org/apache/commons/beanutils/ConstructorUtils.java
@@ -90,12 +90,8 @@ public static <T> Constructor<T> getAccessibleConstructor(
     public static <T> Constructor<T> getAccessibleConstructor(final Constructor<T> ctor) {
 
         // Make sure we have a method to check
-        if (ctor == null) {
-            return null;
-        }
-
         // If the requested method is not public we cannot call it
-        if (!Modifier.isPublic(ctor.getModifiers())) {
+        if (ctor == null || !Modifier.isPublic(ctor.getModifiers())) {
             return null;
         }
 
diff --git a/src/main/java/org/apache/commons/beanutils/ConversionException.java b/src/main/java/org/apache/commons/beanutils/ConversionException.java
index 5cc33969f..a24717041 100644
--- a/src/main/java/org/apache/commons/beanutils/ConversionException.java
+++ b/src/main/java/org/apache/commons/beanutils/ConversionException.java
@@ -32,6 +32,7 @@ public class ConversionException extends RuntimeException {
      *
      * @deprecated Use {@link Throwable#getCause()}}.
      */
+    @Deprecated
     protected Throwable cause;
 
     /**
diff --git a/src/main/java/org/apache/commons/beanutils/MethodUtils.java b/src/main/java/org/apache/commons/beanutils/MethodUtils.java
index fa9ff556c..d0fc5b8c1 100644
--- a/src/main/java/org/apache/commons/beanutils/MethodUtils.java
+++ b/src/main/java/org/apache/commons/beanutils/MethodUtils.java
@@ -206,12 +206,8 @@ public static synchronized int clearCache() {
     public static Method getAccessibleMethod(Class<?> clazz, Method method) {
 
         // Make sure we have a method to check
-        if (method == null) {
-            return null;
-        }
-
         // If the requested method is not public we cannot call it
-        if (!Modifier.isPublic(method.getModifiers())) {
+        if (method == null || !Modifier.isPublic(method.getModifiers())) {
             return null;
         }
 
diff --git a/src/main/java/org/apache/commons/beanutils/PropertyUtilsBean.java b/src/main/java/org/apache/commons/beanutils/PropertyUtilsBean.java
index 4b398eb38..434230d1f 100644
--- a/src/main/java/org/apache/commons/beanutils/PropertyUtilsBean.java
+++ b/src/main/java/org/apache/commons/beanutils/PropertyUtilsBean.java
@@ -136,9 +136,9 @@ private static Map<String, Object> toPropertyMap(final Object obj) {
      * The cache of PropertyDescriptor arrays for beans we have already
      * introspected, keyed by the java.lang.Class of this object.
      */
-    private WeakFastHashMap<Class<?>, BeanIntrospectionData> descriptorsCache;
+    private final WeakFastHashMap<Class<?>, BeanIntrospectionData> descriptorsCache;
 
-    private WeakFastHashMap<Class<?>, FastHashMap> mappedDescriptorsCache;
+    private final WeakFastHashMap<Class<?>, FastHashMap> mappedDescriptorsCache;
 
 
     /** Log instance */
diff --git a/src/main/java/org/apache/commons/beanutils/WrapDynaClass.java b/src/main/java/org/apache/commons/beanutils/WrapDynaClass.java
index dec0a632f..8a01acf55 100644
--- a/src/main/java/org/apache/commons/beanutils/WrapDynaClass.java
+++ b/src/main/java/org/apache/commons/beanutils/WrapDynaClass.java
@@ -269,12 +269,12 @@ private static Map<Object, Object> getDynaClassesMap() {
     /**
      * Name of the JavaBean class represented by this WrapDynaClass.
      */
-    private String beanClassName;
+    private final String beanClassName;
 
     /**
      * Reference to the JavaBean class represented by this WrapDynaClass.
      */
-    private Reference<Class<?>> beanClassRef;
+    private final Reference<Class<?>> beanClassRef;
 
     /** Stores the associated {@code PropertyUtilsBean} instance. */
     private final PropertyUtilsBean propertyUtilsBean;
diff --git a/src/test/java/org/apache/commons/beanutils/converters/BooleanArrayConverterTestCase.java b/src/test/java/org/apache/commons/beanutils/converters/BooleanArrayConverterTestCase.java
index 2af8999d5..a9b45f1e8 100644
--- a/src/test/java/org/apache/commons/beanutils/converters/BooleanArrayConverterTestCase.java
+++ b/src/test/java/org/apache/commons/beanutils/converters/BooleanArrayConverterTestCase.java
@@ -57,7 +57,7 @@ public void testAdditionalStrings() {
         final BooleanConverter bc = new BooleanConverter(
             trueStrings, falseStrings, BooleanConverter.NO_DEFAULT);
         final BooleanArrayConverter converter = new BooleanArrayConverter(
-            bc, BooleanArrayConverter.NO_DEFAULT);
+            bc, AbstractArrayConverter.NO_DEFAULT);
 
         final boolean[] results = (boolean[]) converter.convert(null, "NOPE, sure, sure");
         assertNotNull(results);
@@ -162,7 +162,7 @@ public void testRegistration() {
             trueStrings, falseStrings, BooleanConverter.NO_DEFAULT);
 
         final BooleanArrayConverter converter = new BooleanArrayConverter(
-            bc, BooleanArrayConverter.NO_DEFAULT);
+            bc, AbstractArrayConverter.NO_DEFAULT);
 
         ConvertUtils.register(converter, BooleanArrayConverter.MODEL);
         final boolean[] sample = {};
diff --git a/src/test/java/org/apache/commons/beanutils/converters/SqlTimeConverterTestCase.java b/src/test/java/org/apache/commons/beanutils/converters/SqlTimeConverterTestCase.java
index d5200f43f..d9c1e74e3 100644
--- a/src/test/java/org/apache/commons/beanutils/converters/SqlTimeConverterTestCase.java
+++ b/src/test/java/org/apache/commons/beanutils/converters/SqlTimeConverterTestCase.java
@@ -63,7 +63,7 @@ protected Class<?> getExpectedType() {
 
     private boolean isUSTimeFormatWithNarrowNoBreakSpace() {
         // Fix tests on Java 20 onwards. See https://bugs.openjdk.org/browse/JDK-8324308 for background.
-        DateFormat usDateFormat = DateFormat.getTimeInstance(DateFormat.SHORT, Locale.US);
+        final DateFormat usDateFormat = DateFormat.getTimeInstance(DateFormat.SHORT, Locale.US);
         return ((SimpleDateFormat) usDateFormat).toPattern().contains("\u202F");
     }
 
diff --git a/src/test/java/org/apache/commons/beanutils/converters/SqlTimestampConverterTestCase.java b/src/test/java/org/apache/commons/beanutils/converters/SqlTimestampConverterTestCase.java
index b84e2237a..b03ed75b6 100644
--- a/src/test/java/org/apache/commons/beanutils/converters/SqlTimestampConverterTestCase.java
+++ b/src/test/java/org/apache/commons/beanutils/converters/SqlTimestampConverterTestCase.java
@@ -69,7 +69,7 @@ private boolean isUSFormatWithComma() {
 
     private boolean isUSTimeFormatWithNarrowNoBreakSpace() {
         // Fix tests on Java 20 onwards. See https://bugs.openjdk.org/browse/JDK-8324308 for background.
-        DateFormat usDateFormat = DateFormat.getTimeInstance(DateFormat.SHORT, Locale.US);
+        final DateFormat usDateFormat = DateFormat.getTimeInstance(DateFormat.SHORT, Locale.US);
         return ((SimpleDateFormat) usDateFormat).toPattern().contains("\u202F");
     }
 
diff --git a/src/test/java/org/apache/commons/beanutils/locale/LocaleBeanificationTestCase.java b/src/test/java/org/apache/commons/beanutils/locale/LocaleBeanificationTestCase.java
index da547afab..064085f3c 100644
--- a/src/test/java/org/apache/commons/beanutils/locale/LocaleBeanificationTestCase.java
+++ b/src/test/java/org/apache/commons/beanutils/locale/LocaleBeanificationTestCase.java
@@ -23,6 +23,7 @@
 import java.util.Map;
 import java.util.WeakHashMap;
 
+import org.apache.commons.beanutils.BeanUtilsBean;
 import org.apache.commons.beanutils.ContextClassLoaderLocal;
 import org.apache.commons.beanutils.ConversionException;
 import org.apache.commons.beanutils.ConvertUtils;
@@ -361,7 +362,7 @@ public String toString() {
         assertEquals("Signal not set by test thread", 2, signal.getSignal());
         assertTrue(
                     "Different LocaleBeanUtilsBean instances per context classloader",
-                    LocaleBeanUtilsBean.getInstance() != signal.getBean());
+                    BeanUtilsBean.getInstance() != signal.getBean());
         assertTrue(
                     "Different LocaleConvertUtilsBean instances per context classloader",
                     LocaleConvertUtilsBean.getInstance() != signal.getConvertUtils());