Proposed changes:

Remove getMetadata from connection - if and when it is implemented it will be an optional interface.
Rename Connection.release to close and PoolAwareConnection.releaseCalled to closeCalled
Remove ConnectorCapabilities.supportsExecutionMode and replace Asynch/SynchQuery, Asynch/SynchQueryCommand, Batched Executions with ResultSetExecution, also remove BatchedUpdate and BulkInsert Executions, which can be generalized on UpdateExecution.
BatchedUpdate and BulkInsert support would be indicated by capabilities on ConnectorCapabilities.
Execution mode integer constants would no longer be used, instead the ICommand object would be passed to the Connection.createExecution method.
Asynch Connectors are created by modifying execution logic to throw a DataNotAvailableException, which contains the next poll interval. This removes the need for special executions.
ResultSetExecution would use an iteration approach, which removes the need for Batch and BasicBatch (FEDERATE-311)
Connector batch size would be available on the ExecutionContext, rather than explicitly being passed to the execute method.

Additionally all deprecated classes would be removed and a 5.5. compatibility layer created. Current deprecations are:

Deprecated ConnectorCapabilities scope, and added GlobalCapabilitiesProvider
Deprecated ConnectionPool/DisabledConnectionPool/ConnectionPoolException, since pooling can be provided automatically
Deprecated Asynch/SynchQueryExecution, and added Asynch/SynchQueryCommandExecution