MetricsDynamicMBeanBase throws IllegalArgumentException for empty attribute list

MetricsDynamicMBeanBase.java

@Override
public AttributeList getAttributes(String[] attributeNames) {
if (attributeNames == null || attributeNames.length == 0)
throw new IllegalArgumentException();

The second clause isn't necessary.

There's some code used by management software (RHQ) that occasionally will query with an empty list.

Here is the stack trace.

Caused by: java.lang.IllegalArgumentException
at org.apache.hadoop.metrics.util.MetricsDynamicMBeanBase.getAttributes(MetricsDynamicMBeanBase.java:173)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.getAttributes(DefaultMBeanServerInterceptor.java:726)
at com.sun.jmx.mbeanserver.JmxMBeanServer.getAttributes(JmxMBeanServer.java:665)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1407)
at javax.management.remote.rmi.RMIConnectionImpl.access$200(RMIConnectionImpl.java:72)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1264)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1359)
at javax.management.remote.rmi.RMIConnectionImpl.getAttributes(RMIConnectionImpl.java:636)
at sun.reflect.GeneratedMethodAccessor49.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:305)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
... 3 more