code: public final void setPropositionIds(String[] propIds) {
          if (propIds == null) {
              this.propIds = ArrayUtils.EMPTY_STRING_ARRAY;
          } else {
              this.propIds = propIds.clone();
              ProtempaUtil.internAll(this.propIds);
          }
      }
docs: Sets the proposition ids to be queried. An array of length 0 or
  <code>null</code> means that all proposition ids will be queried.
  
  @param propIds a {@link String[]} of proposition ids. If
  <code>null</code>, an empty {@link String[]} will be stored.