code: public boolean isBaseTypeOf(ModelElementType elementType) {
      if (this.equals(elementType)) {
        return true;
      }
      else {
        Collection<ModelElementType> baseTypes = ModelUtil.calculateAllBaseTypes(elementType);
        return baseTypes.contains(this);
      }
    }
docs: Test if a element type is a base type of this type. So this type extends the given element type.
  
  @param elementType the element type to test
  @return true if {@code childElementTypeClass} is a base type of this type, else otherwise