code: public BUILDER setDefaultValue(ModelNode defaultValue) {
          //noinspection deprecation
          this.defaultValue = (defaultValue == null || !defaultValue.isDefined()) ? null : defaultValue;
          return (BUILDER) this;
      }
docs: Sets a {@link AttributeDefinition#getDefaultValue() default value} to use for the attribute if no
  user-provided value is available.
  @param defaultValue the default value, or {@code null} if no default should be used
  @return a builder that can be used to continue building the attribute definition