Honor Collection.remove() contract in CompositeCollection

Before this commit, `second.remove(o)` was called no matter whether
`first.remove(o)` returned `true` or `false`. If the element was present
in both collections, it was removed from both, which violates the
`Collection.remove(Object)` contract of removing a single instance.

Closes gh-37332

Signed-off-by: Yanming Zhou <zhouyanming@gmail.com>

spring-core/src/main/java/org/springframework/util/CompositeCollection.java

@@ -114,9 +114,7 @@ class CompositeCollection<E extends @Nullable Object> implements Collection<E> {
 
 	@Override
 	public boolean remove(Object o) {
-		boolean firstResult = this.first.remove(o);
-		boolean secondResult = this.second.remove(o);
-		return firstResult || secondResult;
+		return (this.first.remove(o) || this.second.remove(o));
 	}
 
 	@Override

spring-core/src/test/java/org/springframework/util/CompositeCollectionTests.java

@@ -124,8 +124,19 @@ class CompositeCollectionTests {
 		assertThat(composite.remove("foo")).isTrue();
 		assertThat(composite.contains("foo")).isFalse();
 		assertThat(first).containsExactly("bar");
-
 		assertThat(composite.remove("quux")).isFalse();
+
+		// test remove element existing in both first and second
+		first = new ArrayList<>(List.of("foo", "bar"));
+		second = new ArrayList<>(List.of("foo", "qux"));
+		composite = new CompositeCollection<>(first, second);
+
+		assertThat(composite.remove("foo")).isTrue();
+		assertThat(first).containsExactly("bar");
+		assertThat(composite.contains("foo")).isTrue();
+		assertThat(composite.remove("foo")).isTrue();
+		assertThat(second).containsExactly("qux");
+		assertThat(composite.contains("foo")).isFalse();
 	}
 
 	@Test
@@ -207,4 +218,5 @@ class CompositeCollectionTests {
 
 		assertThat(composite).containsExactly("foo", null, "bar", null);
 	}
+
 }