Merging r1580294 from trunk - Don't swallow exception in getLatestVersion. Refactored some odd if conditions.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1580295 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5552: Upgrade JFlex version from 1.5.0 to 1.5.1; also, move @Deprecated class annotation on *TokenizerImplXX.jflex prior to the class comments to workaround JFlex's failure to detect class comments when annotations intervene, which triggers JFlex to auto-generate an additional class comment containing the full path to the .jflex file, which disrupts the use of 'ant regenerate' under different base directories. (merged trunk r1580275)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1580299 13f79535-47bb-0310-9956-ffa450edef68