Specify generic type nullness in spring-expression

See spring-projectsgh-34140

Author: sdeleuze

spring-expression/src/main/java/org/springframework/expression/spel/ast/ConstructorReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -124,7 +124,7 @@ public TypedValue getValueInternal(ExpressionState state) throws EvaluationExcep
 	 * @throws EvaluationException if there is a problem creating the object
 	 */
 	private TypedValue createNewInstance(ExpressionState state) throws EvaluationException {
-		Object[] arguments = new Object[getChildCount() - 1];
+		@Nullable Object[] arguments = new Object[getChildCount() - 1];
 		List<TypeDescriptor> argumentTypes = new ArrayList<>(getChildCount() - 1);
 		for (int i = 0; i < arguments.length; i++) {
 			TypedValue childValue = this.children[i + 1].getValueInternal(state);
@@ -359,7 +359,7 @@ private void checkNumElements(long numElements) {
 	private Object createReferenceTypeArray(ExpressionState state, TypeConverter typeConverter, SpelNodeImpl[] children,
 			Class<?> componentType) {
 
-		Object[] array = (Object[]) Array.newInstance(componentType, children.length);
+		@Nullable Object[] array = (Object[]) Array.newInstance(componentType, children.length);
 		TypeDescriptor targetType = TypeDescriptor.valueOf(componentType);
 		for (int i = 0; i < array.length; i++) {
 			Object value = children[i].getValue(state);

spring-expression/src/main/java/org/springframework/expression/spel/ast/FunctionReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -116,7 +116,7 @@ public TypedValue getValueInternal(ExpressionState state) throws EvaluationExcep
 	 * @throws EvaluationException if there is any problem invoking the method
 	 */
 	private TypedValue executeFunctionViaMethod(ExpressionState state, Method method) throws EvaluationException {
-		Object[] functionArgs = getArguments(state);
+		@Nullable Object[] functionArgs = getArguments(state);
 
 		if (!method.isVarArgs()) {
 			int declaredParamCount = method.getParameterCount();
@@ -175,7 +175,7 @@ private TypedValue executeFunctionViaMethod(ExpressionState state, Method method
 	 * @since 6.1
 	 */
 	private TypedValue executeFunctionViaMethodHandle(ExpressionState state, MethodHandle methodHandle) throws EvaluationException {
-		Object[] functionArgs = getArguments(state);
+		@Nullable Object[] functionArgs = getArguments(state);
 		MethodType declaredParams = methodHandle.type();
 		int spelParamCount = functionArgs.length;
 		int declaredParamCount = declaredParams.parameterCount();
@@ -280,9 +280,9 @@ public String toStringAST() {
 	 * Compute the arguments to the function, they are the children of this expression node.
 	 * @return an array of argument values for the function call
 	 */
-	private Object[] getArguments(ExpressionState state) throws EvaluationException {
+	private @Nullable Object[] getArguments(ExpressionState state) throws EvaluationException {
 		// Compute arguments to the function
-		Object[] arguments = new Object[getChildCount()];
+		@Nullable Object[] arguments = new Object[getChildCount()];
 		for (int i = 0; i < arguments.length; i++) {
 			arguments[i] = this.children[i].getValueInternal(state).getValue();
 		}

spring-expression/src/main/java/org/springframework/expression/spel/ast/MethodReference.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -90,7 +90,7 @@ public final String getName() {
 
 	@Override
 	protected ValueRef getValueRef(ExpressionState state) throws EvaluationException {
-		Object[] arguments = getArguments(state);
+		@Nullable Object[] arguments = getArguments(state);
 		if (state.getActiveContextObject().getValue() == null) {
 			throwIfNotNullSafe(getArgumentTypes(arguments));
 			return ValueRef.NullValueRef.INSTANCE;
@@ -103,14 +103,14 @@ public TypedValue getValueInternal(ExpressionState state) throws EvaluationExcep
 		EvaluationContext evaluationContext = state.getEvaluationContext();
 		Object value = state.getActiveContextObject().getValue();
 		TypeDescriptor targetType = state.getActiveContextObject().getTypeDescriptor();
-		Object[] arguments = getArguments(state);
+		@Nullable Object[] arguments = getArguments(state);
 		TypedValue result = getValueInternal(evaluationContext, value, targetType, arguments);
 		updateExitTypeDescriptor();
 		return result;
 	}
 
 	private TypedValue getValueInternal(EvaluationContext evaluationContext,
-			@Nullable Object value, @Nullable TypeDescriptor targetType, Object[] arguments) {
+			@Nullable Object value, @Nullable TypeDescriptor targetType, @Nullable Object[] arguments) {
 
 		List<TypeDescriptor> argumentTypes = getArgumentTypes(arguments);
 		if (value == null) {
@@ -167,8 +167,8 @@ private void throwIfNotNullSafe(List<TypeDescriptor> argumentTypes) {
 		}
 	}
 
-	private Object[] getArguments(ExpressionState state) {
-		Object[] arguments = new Object[getChildCount()];
+	private @Nullable Object[] getArguments(ExpressionState state) {
+		@Nullable Object[] arguments = new Object[getChildCount()];
 		for (int i = 0; i < arguments.length; i++) {
 			// Make the root object the active context again for evaluating the parameter expressions
 			try {
@@ -182,8 +182,8 @@ private Object[] getArguments(ExpressionState state) {
 		return arguments;
 	}
 
-	private List<TypeDescriptor> getArgumentTypes(Object... arguments) {
-		List<TypeDescriptor> descriptors = new ArrayList<>(arguments.length);
+	private List<TypeDescriptor> getArgumentTypes(@Nullable Object... arguments) {
+		List<@Nullable TypeDescriptor> descriptors = new ArrayList<>(arguments.length);
 		for (Object argument : arguments) {
 			descriptors.add(TypeDescriptor.forObject(argument));
 		}
@@ -380,9 +380,9 @@ private class MethodValueRef implements ValueRef {
 
 		private final @Nullable TypeDescriptor targetType;
 
-		private final Object[] arguments;
+		private final @Nullable Object[] arguments;
 
-		public MethodValueRef(ExpressionState state, Object[] arguments) {
+		public MethodValueRef(ExpressionState state, @Nullable Object[] arguments) {
 			this.evaluationContext = state.getEvaluationContext();
 			this.value = state.getActiveContextObject().getValue();
 			this.targetType = state.getActiveContextObject().getTypeDescriptor();

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectionHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -250,7 +250,7 @@ else if (typeConverter.canConvert(suppliedArg, TypeDescriptor.valueOf(varargsCom
 	 * @return {@code true} if some kind of conversion occurred on an argument
 	 * @throws SpelEvaluationException if a problem occurs during conversion
 	 */
-	public static boolean convertAllArguments(TypeConverter converter, Object[] arguments, Method method)
+	public static boolean convertAllArguments(TypeConverter converter, @Nullable Object[] arguments, Method method)
 			throws SpelEvaluationException {
 
 		Integer varargsPosition = (method.isVarArgs() ? method.getParameterCount() - 1 : null);
@@ -269,7 +269,8 @@ public static boolean convertAllArguments(TypeConverter converter, Object[] argu
 	 * @return {@code true} if some kind of conversion occurred on an argument
 	 * @throws EvaluationException if a problem occurs during conversion
 	 */
-	static boolean convertArguments(TypeConverter converter, Object[] arguments, Executable executable,
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
+	static boolean convertArguments(TypeConverter converter, @Nullable Object[] arguments, Executable executable,
 			@Nullable Integer varargsPosition) throws EvaluationException {
 
 		boolean conversionOccurred = false;
@@ -359,7 +360,8 @@ else if (!sourceType.isAssignableTo(componentTypeDesc) ||
 	 * @throws EvaluationException if a problem occurs during conversion
 	 * @since 6.1
 	 */
-	public static boolean convertAllMethodHandleArguments(TypeConverter converter, Object[] arguments,
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
+	public static boolean convertAllMethodHandleArguments(TypeConverter converter, @Nullable Object[] arguments,
 			MethodHandle methodHandle, @Nullable Integer varargsPosition) throws EvaluationException {
 
 		boolean conversionOccurred = false;
@@ -453,7 +455,7 @@ else if (!sourceType.isAssignableTo(varargsComponentType) ||
 	 * @param possibleArray an array object that may have the supplied value as the first element
 	 * @return true if the supplied value is the first entry in the array
 	 */
-	private static boolean isFirstEntryInArray(Object value, @Nullable Object possibleArray) {
+	private static boolean isFirstEntryInArray(@Nullable Object value, @Nullable Object possibleArray) {
 		if (possibleArray == null) {
 			return false;
 		}
@@ -477,7 +479,7 @@ private static boolean isFirstEntryInArray(Object value, @Nullable Object possib
 	 * @param args the arguments to be set up for the invocation
 	 * @return a repackaged array of arguments where any varargs setup has been performed
 	 */
-	public static Object[] setupArgumentsForVarargsInvocation(Class<?>[] requiredParameterTypes, Object... args) {
+	public static @Nullable Object[] setupArgumentsForVarargsInvocation(Class<?>[] requiredParameterTypes, @Nullable Object... args) {
 		Assert.notEmpty(requiredParameterTypes, "Required parameter types array must not be empty");
 
 		int parameterCount = requiredParameterTypes.length;
@@ -491,7 +493,7 @@ public static Object[] setupArgumentsForVarargsInvocation(Class<?>[] requiredPar
 		// Check if repackaging is needed...
 		if (parameterCount != argumentCount || !lastRequiredParameterType.isInstance(lastArgument)) {
 			// Create an array for the leading arguments plus the varargs array argument.
-			Object[] newArgs = new Object[parameterCount];
+			@Nullable Object[] newArgs = new Object[parameterCount];
 			// Copy all leading arguments to the new array, omitting the varargs array argument.
 			System.arraycopy(args, 0, newArgs, 0, newArgs.length - 1);
 

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectiveConstructorExecutor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -52,7 +52,7 @@ public ReflectiveConstructorExecutor(Constructor<?> ctor) {
 	}
 
 	@Override
-	public TypedValue execute(EvaluationContext context, Object... arguments) throws AccessException {
+	public TypedValue execute(EvaluationContext context, @Nullable Object... arguments) throws AccessException {
 		try {
 			ReflectionHelper.convertArguments(
 					context.getTypeConverter(), arguments, this.ctor, this.varargsPosition);

spring-expression/src/main/java/org/springframework/expression/spel/support/ReflectiveMethodExecutor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -102,7 +102,7 @@ public boolean didArgumentConversionOccur() {
 
 
 	@Override
-	public TypedValue execute(EvaluationContext context, Object target, Object... arguments) throws AccessException {
+	public TypedValue execute(EvaluationContext context, Object target, @Nullable Object... arguments) throws AccessException {
 		try {
 			this.argumentConversionOccurred = ReflectionHelper.convertArguments(
 					context.getTypeConverter(), arguments, this.originalMethod, this.varargsPosition);