Fix declaration of ConcurrentHashMap instance

This should prevent issues with running 1.8-compiled classes on 1.6 or 1.7.
Merge pull request #1286 from melissalinkert/rebased/develop/concurrent-hash-map

Fix declaration of ConcurrentHashMap instance (rebased onto develop)
Update auto-generated documentation

Repository: openmicroscopy/bioformats
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Generated by BIOFORMATS-5.1-latest-docs-autogen#124 (http://ci.openmicroscopy.org/job/BIOFORMATS-5.1-latest-docs-autogen/124/)