[50%] Phase 3: Convert Kotlin to Java

[evanchooly]

Parent: #4179
Blocked by: #4185

Goal

Convert all critter-core Kotlin sources to Java to eliminate the Kotlin runtime dependency and simplify the build to pure Java.

Details

See Phase 3 in planning doc

Tasks

• Convert critter-core test sources from Kotlin to Java (all tests must pass against existing Kotlin production code)
• Convert critter-core main sources from Kotlin to Java (leave tests unchanged where possible)

Progress Tracking

phase_percentage = (completed_tasks / 2) * 100, rounded to nearest integer
gh issue edit <THIS_ISSUE> --repo MorphiaOrg/morphia --title "[XX%] Phase 3: Convert Kotlin to Java"

parent_percentage = (total_completed_tasks_across_all_phases / 55) * 100, rounded to nearest integer
gh issue edit 4179 --repo MorphiaOrg/morphia --title "[XX%] Integrate critter-core into morphia-core"

When all tasks are complete (100%), close this issue and check its box in #4179.