Bug system: https://bugs.openjdk.java.net

JDK-8193292: Add SourceVersion.RELEASE_12
JDK-8208201: Update SourceVersion.RELEASE_11 docs to mention var for lambda param
JDK-8213256: Clarify runtime vs compile time annotations for RoundEnvironment.getElementsAnnotatedWith(Class)
JDK-8208200: Add missing periods to sentences in RoundEnvironment specs
JDK-8173606: Deprecate constructors of 7-era visitors
JDK-8216322: Missing since information in deprecation of constructor visitors