Front-End:

• Global experience with on Web front technology, ideally Angular and/or React
• Experience with hybrid App solution and technology (Cordova or else)

Back-end:

• Java for sure and more JEE.
• Some frameworks linked to : dependencies injection (Struts), and database mapping (Hibernate of equivalent)
• SAP interface framework
• API design (Rest / JSON API, others)

Databases:

• SQL base: a must
• NoSQL: some skills
• Environment (Devops):
• Virtual Machine skills
• Containers / Dockers