void validateQuotaTarget(QuotaSettings mergee) {
    if (!Objects.equals(getUserName(), mergee.getUserName())) {
      throw new IllegalArgumentException("Mismatched user names on settings to merge");
    }
    if (!Objects.equals(getTableName(), mergee.getTableName())) {
      throw new IllegalArgumentException("Mismatched table names on settings to merge");
    }
    if (!Objects.equals(getNamespace(), mergee.getNamespace())) {
      throw new IllegalArgumentException("Mismatched namespace on settings to merge");
    }
    if (!Objects.equals(getRegionServer(), mergee.getRegionServer())) {
      throw new IllegalArgumentException("Mismatched region server on settings to merge");
    }
  }
Validates that settings being merged into {@code this} is targeting the same "subject", e.g.
user, table, namespace.
@param mergee The quota settings to be merged into {@code this}.
@throws IllegalArgumentException if the subjects are not equal.
hbase-client/src/main/java/org/apache/hadoop/hbase/quotas/QuotaSettings.java