Base: Concurrency, NIO, JNI, Annotation Processor Writing, Bytecode Patching.
Android specific: Class-loaders, GC Specific, Google Transform API, Off-Heap Solutions, Dalvik, ART, Performance Analysis, SDK/api/library writing, persistence.
Java SE specific: JPA, JDBC, spring (boot, MVC, WEB, data, JPA, mongo), Hibernate, Netty, Undertow.
Dear HR'S. Please, do not suggest for me working with all kind of product features stuff, except only things like above or relevant experience by my last work position.
Standing resident of largest Russian Android development podcast:
Droidcon Moscow '16/17 speaker.
DevFest '16/17 Novosibirsk speaker.
MosDroid meetups periodical speaker.