code: @Override
      public String permissionsToString() {
          if (this.permissions == null) {
              return Constants.EMPTY_STRING;
          }
  
          // The service supports a fixed order => raup
          final StringBuilder builder = new StringBuilder();
  
          if (this.permissions.contains(SharedAccessQueuePermissions.READ)) {
              builder.append("r");
          }
  
          if (this.permissions.contains(SharedAccessQueuePermissions.ADD)) {
              builder.append("a");
          }
  
          if (this.permissions.contains(SharedAccessQueuePermissions.UPDATE)) {
              builder.append("u");
          }
  
          if (this.permissions.contains(SharedAccessQueuePermissions.PROCESSMESSAGES)) {
              builder.append("p");
          }
  
          return builder.toString();
      }
docs: Converts this policy's permissions to a string.
  
  @return A <code>String</code> that represents the shared access permissions in the "raup" format, which is
  described at {@link SharedAccessQueuePolicy#setPermissionsFromString(String)}.