Added 'closeLeakedConnections' property which enables leaked connections closing.

[rgorodischer]

closeLeakedConnections property controls whether unreturned connection must be closed automatically after being used longer than the time limit specified by leakDetectionThreshold property.

The true value for this property is only valid when a positive value for the connection leak
detection threshold is specified. False by default.

[brettwooldridge]

Thanks for the contribution, Roman. Unfortunately, this is not a property we are interested in adding to the pool. Of course as we surveyed other pools before building HikariCP we encountered pools that offer this as an option.

However, we disagree in principal that a pool should act to cover-up what are in effect defects in the application layer. If there were no pool present, such a defect would exhaust the available connections of the underlying database, and eventually fail. The pool should not mask or make such a defect transparent.

If this functionality is somehow critical to your application, you are free to maintain a fork of HikariCP of course, or consider a fairly reliable alternative such as the Tomcat JDBC pool.

[brettwooldridge]

BTW, the quality of the code in the request was quite good.