docs: public void setAbstractTopic(final SpecTopic abstractTopic) {
          if (abstractTopic == null && this.abstractTopic == null) {
              return;
          } else if (abstractTopic == null) {
              removeChild(this.abstractTopic);
              this.abstractTopic = null;
          } else if (this.abstractTopic == null) {
              abstractTopic.setTopicType(TopicType.ABSTRACT);
              this.abstractTopic = new KeyValueNode<SpecTopic>(CommonConstants.CS_ABSTRACT_TITLE, abstractTopic);
              appendChild(this.abstractTopic, false);
          } else {
              abstractTopic.setTopicType(TopicType.ABSTRACT);
              this.abstractTopic.setValue(abstractTopic);
          }
      }