code: protected final void addContentPart(List<ContentPart<?>> contentList,String key,String value)
      {
          if((key!=null)&&(value!=null)&&(value.length()>0))
          {
              if(this.shouldAddContentPart(key))
              {
                  contentList.add(new ContentPart<String>(key,value,ContentPartType.STRING));
              }
          }
      }
docs: This function adds a string content part
  
  @param   contentList
  The content list with all the created parts
  @param   key
  The parameter key
  @param   value
  The parameter value