code: public BUILDER setXmlName(String xmlName) {
          //noinspection deprecation
          this.xmlName = xmlName == null ? this.name : xmlName;
          return (BUILDER) this;
      }
docs: Sets the {@link AttributeDefinition#getXmlName() xml name} for the attribute, which is only needed
  if the name used for the attribute is different from its ordinary
  {@link AttributeDefinition#getName() name in the model}. If not set the default value is the name
  passed to the builder constructor.
  
  @param xmlName the xml name. {@code null} is allowed
  @return a builder that can be used to continue building the attribute definition