Technology Road map for Java developers:

JAVA core (8-11-17)
Java Stream API, OOP, Algorithms – Book: – Java Basic Book
Database: 1) SQL (MySQL, Oracle) 2) NoSQL (MongoDB, Cassandra)
Framework: Spring, Spring Boot, Spring Security
Messages System: Apache Kafka
Work Environment (IDE): IntelJ IDEA, Eclipse

Additional:
Web-servers: Apache Tomcat.
Docker, Kubernetes

Good to know: Unix (any Linux), Hadoop, , Amazon AWS