Speed up consequent Java validation

[vadi2]

Is your feature request related to a problem? Please describe. Consequent .NET validation is much quicker because the specification is already loaded - but this isn't the case for Java, which has to load the specification every time.

Describe the solution you'd like Perhaps some long-running Java process and do IPC to it? Not sure on the design yet - ideas welcome.

Additional context Any resulting solution needs to work on Windows, macOS, and Linux.