protected String ownerToString() {
    StringBuilder builder = new StringBuilder();
    if (userName != null) {
      builder.append("USER => '");
      builder.append(userName);
      builder.append("', ");
    }
    if (tableName != null) {
      builder.append("TABLE => '");
      builder.append(tableName.toString());
      builder.append("', ");
    }
    if (namespace != null) {
      builder.append("NAMESPACE => '");
      builder.append(namespace);
      builder.append("', ");
    }
    if (regionServer != null) {
      builder.append("REGIONSERVER => ").append(regionServer).append(", ");
    }
    return builder.toString();
  }
Called by toSetQuotaRequestProto() the subclass should implement this method to set the
specific SetQuotaRequest properties.
hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaSettings.java