code: public java.util.List<PrincipalIdFormat> getPrincipals() {
          if (principals == null) {
              principals = new com.amazonaws.internal.SdkInternalList<PrincipalIdFormat>();
          }
          return principals;
      }
docs: <p>
  Information about the ID format settings for the ARN.
  </p>
  
  @return Information about the ID format settings for the ARN.