Speculative fix for cross-thread visibility issue.
Merge branch 'dev' of github.com:brettwooldridge/HikariCP into dev

# By Brett Wooldridge (3) and Guillaume Smet (3)
* 'dev' of github.com:brettwooldridge/HikariCP:
  More clean-up/tighten-up of code.
  More clean-up/tighten-up of code.
  Fix typo: s/&/&&/.
  Use entrySet() instead of keySet().
  Make leakTrace local as there is no need to make it an attribute.
  Use some static imports.