Remove @⁠Contract declaration for CodeFlow.isIntegerForNumericOp()

Since the Number parameter is not @⁠Nullable, the @⁠Contract declaration
is unnecessary.

Closes gh-34985

spring-expression/src/main/java/org/springframework/expression/spel/CodeFlow.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.
@@ -691,9 +691,8 @@ public class CodeFlow implements Opcodes {
 	 * Determine whether the given number is to be considered as an integer
 	 * for the purposes of a numeric operation at the bytecode level.
 	 * @param number the number to check
-	 * @return {@code true} if it is an {@link Integer}, {@link Short} or {@link Byte}
+	 * @return {@code true} if it is an {@link Integer}, {@link Short}, or {@link Byte}
 	 */
-	@Contract("null -> false")
 	public static boolean isIntegerForNumericOp(Number number) {
 		return (number instanceof Integer || number instanceof Short || number instanceof Byte);
 	}