code: public static boolean canAcceptParent(Class<? extends ElementBase> childClass,
                                            Class<? extends ElementBase> parentClass) {
          return allowedParentClasses.isRelated(childClass, parentClass);
      }
docs: Returns true if parentClass can be a parent of childClass.
  
  @param childClass The child class.
  @param parentClass The parent class.
  @return True if parentClass can be a parent of childClass.