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Guide for upgrading Java projects between major versions (8→11→17→21→25).
Passed 22 of 22 test cases with the skill, and 19 of 22 without it.
and 1 more in the full report
3 fixed19 passed either way0 still failing0 broke
Tokens, turns and time describe resource use, not a dollar price.
One of 3 test cases the skill fixed. Same model, same prompt, with and without the skill.
Our unit tests pass on Java 17 but throw bytecode manipulation errors when running test suites on Java 21 with Mockito 3.x. What Mockito version major line resolves Java 21 compatibility?
| Checked | Without skill | With skill |
|---|---|---|
| Recommends updating Mockito to version 5.8.0 or higher | Missed | Passed |
The instructions your model reads when the skill loads.
Step-by-step guide for upgrading Java projects between major versions.
Java 8 (LTS) → Java 11 (LTS) → Java 17 (LTS) → Java 21 (LTS) → Java 25 (LTS)
│ │ │ │ │
└──────────────┴───────────────┴──────────────┴───────────────┘
Always migrate LTS → LTS
| From → To | Major Breaking Changes |
|---|---|
| 8 → 11 | Removed javax.xml.bind, module system, internal APIs |
| 11 → 17 | Sealed classes (preview→final), strong encapsulation |
| 17 → 21 | Pattern matching changes, finalize() deprecated for removal |
| 21 → 25 | Security Manager removed, Unsafe methods removed, 32-bit dropped |
# Check current Java version
java -version
test cases passed, vs 19 / 22 without
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