ClassUtils: fix javadoc for annotated list results

What was written in the javadoc used to be true, but for performance
reasons, we added a cache for situations where the same request is
made multiple times. This commit updates the javadoc to reflect the
new reality.

Closes #252.

Author: ctrueden

src/main/java/org/scijava/util/ClassUtils.java

@@ -364,7 +364,9 @@ public static URL getLocation(final Class<?> c) {
 	 *
 	 * @param c The class to scan for annotated methods.
 	 * @param annotationClass The type of annotation for which to scan.
-	 * @return A new list containing all methods with the requested annotation.
+	 * @return A list containing all methods with the requested annotation. Note
+	 *         that for performance reasons, lists may be cached and reused, so it
+	 *         is best to make a copy of the result if you need to modify it.
 	 */
 	public static <A extends Annotation> List<Method> getAnnotatedMethods(
 		final Class<?> c, final Class<A> annotationClass)
@@ -417,7 +419,9 @@ public static <A extends Annotation> List<Method> getAnnotatedMethods(
 	 *
 	 * @param c The class to scan for annotated fields.
 	 * @param annotationClass The type of annotation for which to scan.
-	 * @return A new list containing all fields with the requested annotation.
+	 * @return A list containing all fields with the requested annotation. Note
+	 *         that for performance reasons, lists may be cached and reused, so it
+	 *         is best to make a copy of the result if you need to modify it.
 	 */
 	public static <A extends Annotation> List<Field> getAnnotatedFields(
 		final Class<?> c, final Class<A> annotationClass)