Update java.md

lang/java.md

@@ -39,3 +39,28 @@ sudo ln -s ~/.local/share/mise/installs/java/openjdk-20/Contents /Library/Java/J
 The Java core plugin supports the legacy version files `.java-version` and `.sdkmanrc`.
 
 For `.sdkmanrc` files, mise will try to map the vendor and version to the appropriate version string. For example, the version `20.0.2-tem` will be mapped to `temurin-20.0.2`. Due to Azul's Zulu versioning, the version `11.0.12-zulu` will be mapped to the major version `zulu-11`. Not all vendors available in SDKMAN are supported by mise. The following vendors are NOT supported: `bsg` (Bisheng), `graal` (GraalVM), `nik` (Liberica NIK).
+
+In case an unsupported version of java is needed, some manual work is required:
+
+1. Download the unsupported version to a directory (e.g `~/.sdkman/candidates/java/21.0.1-open`)
+2. symlink the new version:
+   ```sh
+   ln -s ~/.sdkman/candidates/java/21.0.1-open ~/.local/share/mise/installs/java/21.0.1-open
+   ```
+3. If on Mac:
+  ```sh
+  mkdir ~/.local/share/mise/installs/java/21.0.1-open/Contents
+  mkdir ~/.local/share/mise/installs/java/21.0.1-open/Contents/MacOS
+
+  ln -s ~/.sdkman/candidates/java/21.0.1-open ~/.local/share/mise/installs/java/21.0.1-open/Contents/Home
+  cp ~/.local/share/mise/installs/java/21.0.1-open/lib/libjli.dylib ~/.local/share/mise/installs/java/21.0.1-open/Contents/MacOS/libjli.dylib
+  ```
+4. Don't forget to make sure the cache is blocked and valid, by making sure an **empty** directory **exists** for your version in the [mise cache](https://mise.jdx.dev/directories.html#cache-mise):
+   e.g.
+   ```sh
+   $ ls -R $MISE_CACHE_DIR/java
+   21.0.1-open
+
+   mise/java/21.0.1-open:
+
+   ```