Issue #5032 - Adding requested javadoc

Signed-off-by: Joakim Erdfelt <joakim.erdfelt@gmail.com>

jetty-servlet/src/main/java/org/eclipse/jetty/servlet/BaseHolder.java

@@ -186,6 +186,15 @@ public synchronized boolean isInstance()
         return _instance != null;
     }
 
+    /**
+     * Wrap component using component specific Wrapper Function beans.
+     *
+     * @param component the component to optionally wrap
+     * @param wrapperFunctionType the bean class type to look for in the {@link ServletContextHandler}
+     * @param function the BiFunction to execute for each {@code wrapperFunctionType} Bean found (passing in the component and component type)
+     * @param <W> the "wrapper function" implementation. (eg: {@code ServletHolder.WrapperFunction} or {@code FilterHolder.WrapperFunction}, etc)
+     * @return the component that has passed through all Wrapper Function beans found.
+     */
     protected <W> T wrap(final T component, final Class<W> wrapperFunctionType, final BiFunction<W, T, T> function)
     {
         T ret = component;