code: public String getDatasource() {
          if (datasourceName == null) {
              CharSequence name = getStaticPropertyValue(DATA_SOURCE, CharSequence.class);
              datasourceName = name == null ? null : name.toString();
              if (datasourceName == null) {
                  datasourceName = DEFAULT_DATA_SOURCE;
              }
          }
  
          return datasourceName;
      }
docs: If service is transactional then get data source will always apply
  
  @return name of data source