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

JDK-8267631: Add SourceVersion.RELEASE_18
JDK-8273157: Add convenience methods to Messager
JDK-8275368: Correct statement of kinds of elements Processor.process operates over
JDK-8140442: Add getOutermostTypeElement to javax.lang.model utility class
JDK-8275308: Add valueOf(Runtime.Version) factory to SourceVersion
JDK-8276772: Refine javax.lang.model docs
JDK-8224922: Access JavaFileObject from Element(s)
JDK-8277303: Terminology mismatch between JLS17-3.9 and SE17's javax.lang.model.SourceVersion method specs
JDK-8265888: StandardJavaFileManager::setLocationForModule specification misses 'Implementation Requirements:'