code: public static Method getWholeMethod(Class<?> clazz, String methodName, Class<?>[] argTypes) {
          assertObjectNotNull("clazz", clazz);
          assertStringNotNullAndNotTrimmedEmpty("methodName", methodName);
          return findMethod(clazz, methodName, argTypes, VisibilityType.WHOLE, false);
      }
docs: Get the method in whole methods that means as follows:
  <pre>
  o target class's methods = all
  o superclass's methods   = all (also contains private)
  </pre>
  And no cache so you should cache it yourself if you call several times.
  @param clazz The type of class that defines the method. (NotNull)
  @param methodName The name of method. (NotNull)
  @param argTypes The type of argument. (NotNull)
  @return The instance of method. (NullAllowed: if null, not found)