public DataOutput getDataOutput() {
            return new DataOutputStream( baos );
        }
Utility class that generates a DataOutput and DataInput that share a common resource, meaning that what is
written to the DataOutput becomes available for reading on the DataInput.

Instances are single-use. DataOutput should be written to before DataInput is obtained (this implementation was
designed for unit testing only, not for re-use elsewhere).
xmppserver/src/test/java/org/jivesoftware/util/cache/DefaultExternalizableUtilTest.java