Converted DefaultConnectionProviderTest into a Spock Specification, and tried to simplify the test and make it more readable.  This involved trimming down and refactoring some of the test helper classes.
Updated DefaultConnectionProviderSpecification as a result of code review feedback - added a test to show expected behaviour around close() and isClosed(); updated timeout numbers to cater for Groovy's slower runtime; removed timeout from test that didn't need it (and was giving false positives because of it).