Nodepool NodeMetadataStoreTest.testDeleteMapping fails on Windows

[demobox]

mvn clean test run against d8a2bff (Windows 7, JDK 1.6.0_20 and 1.7.0_07)

Failed tests:   testDeleteMapping(org.jclouds.nodepool.NodeMetadataStoreTest): e
xpected [null] but found [{id=testmeta1, group=testgroup, status=ERROR, loginPor
t=22, loginUser=testuser, tags=[tag1, tag2], userMetadata={testmetakey=testmetav
alue, testmetakey2=testmetavalue2}}]

The underlying problem is described in this issue that was not (yet) migrated from Google Code: since JsonNodeMetadataStore's "delete" implementation calls InputStreamMap.remove.

There doesn't seem to be any real solution here other than either

• documenting nodepool as not being (fully) compatible with Windows or
• replacing the call to InputStreamMap.remove with something else or
• implementing this suggestion and using the LoadingCache abstraction in place of the InputStreamMap

@adriancole @dralves Thoughts?