Bad practice - Method with Boolean return type returns explicit null

Use Optional instead, where Optional.empty() corresponds to null.

org.eclipse.wb.core.java/src/org/eclipse/wb/internal/core/model/JavaInfoUtils.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2011, 2023 Google, Inc.
+ * Copyright (c) 2011, 2024 Google, Inc.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -680,7 +680,7 @@ private static void addExposedJavaInfo(JavaInfo host, JavaInfo exposed) throws E
 	private static boolean isEnabledExposeMethod(JavaInfo host, Method getMethod) {
 		// check filters
 		for (ExposingRule rule : host.getDescription().getExposingRules()) {
-			Boolean filter = rule.filter(getMethod);
+			Boolean filter = rule.filter(getMethod).orElse(null);
 			if (filter != null) {
 				if (filter.booleanValue()) {
 					return true;
@@ -707,7 +707,7 @@ private static boolean isEnabledExposeMethod(JavaInfo host, Method getMethod) {
 	private static boolean isEnabledExposeField(JavaInfo host, Field field) {
 		// check filters
 		for (ExposingRule rule : host.getDescription().getExposingRules()) {
-			Boolean filter = rule.filter(field);
+			Boolean filter = rule.filter(field).orElse(null);
 			if (filter != null) {
 				if (filter.booleanValue()) {
 					return true;

org.eclipse.wb.core.java/src/org/eclipse/wb/internal/core/model/description/ExposingMethodRule.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2011 Google, Inc.
+ * Copyright (c) 2011, 2024 Google, Inc.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -13,6 +13,7 @@
 import org.eclipse.wb.internal.core.utils.check.Assert;
 
 import java.lang.reflect.Method;
+import java.util.Optional;
 
 /**
  * Implementation of {@link ExposingRule} that name of given {@link Method}.
@@ -40,13 +41,13 @@ public ExposingMethodRule(boolean include, String methodName) {
 	//
 	////////////////////////////////////////////////////////////////////////////
 	@Override
-	public Boolean filter(Method method) {
+	public Optional<Boolean> filter(Method method) {
 		Assert.isLegal(method.getParameterTypes().length == 0, method.toString());
 		// check method name
 		if (!method.getName().equals(m_methodName)) {
-			return null;
+			return Optional.empty();
 		}
 		// OK, method satisfies to filter, so include/exclude it
-		return m_include;
+		return Optional.of(m_include);
 	}
 }

org.eclipse.wb.core.java/src/org/eclipse/wb/internal/core/model/description/ExposingPackageRule.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2011 Google, Inc.
+ * Copyright (c) 2011, 2024 Google, Inc.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -14,6 +14,7 @@
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
+import java.util.Optional;
 
 /**
  * Implementation of {@link ExposingRule} that checks package of {@link Class} declaring given
@@ -42,20 +43,20 @@ public ExposingPackageRule(boolean include, String packageName) {
 	//
 	////////////////////////////////////////////////////////////////////////////
 	@Override
-	public Boolean filter(Method method) {
+	public Optional<Boolean> filter(Method method) {
 		String packageName = CodeUtils.getPackage(method.getDeclaringClass().getName());
 		if (packageName.equals(m_packageName)) {
-			return m_include;
+			return Optional.of(m_include);
 		}
-		return null;
+		return Optional.empty();
 	}
 
 	@Override
-	public Boolean filter(Field field) {
+	public Optional<Boolean> filter(Field field) {
 		String packageName = CodeUtils.getPackage(field.getDeclaringClass().getName());
 		if (packageName.equals(m_packageName)) {
-			return m_include;
+			return Optional.of(m_include);
 		}
-		return null;
+		return Optional.empty();
 	}
 }

org.eclipse.wb.core.java/src/org/eclipse/wb/internal/core/model/description/ExposingRule.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2011 Google, Inc.
+ * Copyright (c) 2011, 2024 Google, Inc.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -12,6 +12,7 @@
 
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
+import java.util.Optional;
 
 /**
  * Filter for checking that some {@link Method} can be used to expose child.
@@ -25,22 +26,22 @@ public abstract class ExposingRule {
 	 *          the {@link Method} to filter.
 	 *
 	 * @return <code>true</code> if given {@link Method} can be used to expose child,
-	 *         <code>false</code> - if can not be exposed, or <code>null</code> if given
+	 *         <code>false</code> - if can not be exposed, or <code>empty</code> if given
 	 *         {@link Method} does not fall into this rule.
 	 */
-	public Boolean filter(Method method) {
-		return null;
+	public Optional<Boolean> filter(Method method) {
+		return Optional.empty();
 	}
 
 	/**
 	 * @param method
 	 *          the {@link Field} to filter.
 	 *
 	 * @return <code>true</code> if given {@link Field} can be used to expose child,
-	 *         <code>false</code> - if can not be exposed, or <code>null</code> if given {@link Field}
+	 *         <code>false</code> - if can not be exposed, or <code>empty</code> if given {@link Field}
 	 *         does not fall into this rule.
 	 */
-	public Boolean filter(Field field) {
-		return null;
+	public Optional<Boolean> filter(Field field) {
+		return Optional.empty();
 	}
 }