Having just taken a job with Raytheon and lamenting my lack of success getting a top software development position in a startup a friend ask "What is needed for new startups?"
As to the Java language and its ecology, this has little interest for them. In fact, many of the infrastructure foundations that are today implemented in Java -- ActiveMQ, Kafka, Zookeeper, Tomcat, etc -- are being replaced with "lighter" Go and Rust implementations. And with the accelerating move to managed infrastructure startups care little about how these foundations are implemented. They would rather rent, eg, a queuing service from AWS or GCP, and let the provider worry about implementing turnkey, scalable performance.
Even Citizens Bank, after having recently become independent of the Royal Bank of Scotland, is replacing their Java J2EE implementation with an AWS hosted, node.js microserviced, and React front ends. I have even heard that some of their services are from a "bank in a box" supplier.