@Override
    protected void buildAuditMessage(StringBuilder builder) {
      super.buildAuditMessage(builder);

      builder.append(", Group(")
        .append(groupName)
        .append("), Members(");

      if (userNameList.isEmpty()) {
        builder.append("<empty>");
      } else {
        builder.append(StringUtils.join(userNameList, ", "));
      }

      builder.append(")");
    }
Appends to the event the details of the incoming request.

@param builder builder for the audit event details.
ambari-server/src/main/java/org/apache/ambari/server/audit/event/request/MembershipChangeRequestAuditEvent.java