fix(java): pass the configured Maven local repository to jdtls (#1813)

m2e resolves and downloads into maven.repo.local, which neither the
userSettings init option nor MAVEN_OPTS covers. Without it the embedded
Maven fell back to ~/.m2 even when every mvn run the IDE launches used
the configured repository, splitting the cache across two locations.

A -Dmaven.repo.local in the user's own jdtls VM options wins.

Fixes #1739

crates/ide-sdk/src/apply.rs

@@ -798,6 +798,22 @@ pub fn configure_server(cfg: &mut LanguageServerConfig, root: &Path, server_root
                 json!({ "settings": { "java": { "configuration": { "maven": { "userSettings": file } } } } }),
             );
         }
+        // m2e resolves and downloads into `maven.repo.local`; without it the
+        // embedded Maven falls back to ~/.m2 even when the IDE's own `mvn`
+        // runs honor the configured local repository. A `-Dmaven.repo.local`
+        // the user put in their own jdtls VM options wins.
+        if let Some(repo) = maven_local_repository(root, s) {
+            let arg = format!("-Dmaven.repo.local={}", repo.to_string_lossy());
+            let taken = cfg.args.iter().enumerate().any(|(i, a)| {
+                let value = a
+                    .strip_prefix("--jvm-arg=")
+                    .or_else(|| (i > 0 && cfg.args[i - 1] == "--jvm-arg").then_some(a.as_str()));
+                value.is_some_and(|a| a.split('=').next() == Some("-Dmaven.repo.local"))
+            });
+            if !taken {
+                cfg.args.push(format!("--jvm-arg={arg}"));
+            }
+        }
     }
 
     if let Some(lib) = tsdk(server_root, s).or_else(|| tsdk(root, s)) {

crates/ide-sdk/src/tests.rs

@@ -115,6 +115,26 @@ fn jdtls_vm_args() {
     assert_eq!(cfg.args, ["--jvm-arg=-Xmx2g", "--jvm-arg=-javaagent:/opt/lombok.jar"]);
 }
 
+#[test]
+fn jdtls_honors_the_configured_maven_local_repository() {
+    let tmp = tempfile::tempdir().unwrap();
+    let repo = tmp.path().join("m2-repo");
+    let mut s = Settings::default();
+    s.languages.java.maven.local_repository = repo.to_string_lossy().into_owned();
+    let mut cfg = server("jdtls");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    assert_eq!(cfg.args, [format!("--jvm-arg=-Dmaven.repo.local={}", repo.to_string_lossy())]);
+    // A `-Dmaven.repo.local` the user put in their own jdtls VM options wins.
+    s.languages.java.jdtls_vm_args = "-Xmx2g -Dmaven.repo.local=/user/repo".into();
+    let mut cfg = server("jdtls");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    assert_eq!(cfg.args, ["--jvm-arg=-Xmx2g", "--jvm-arg=-Dmaven.repo.local=/user/repo"]);
+    // Unset: jdtls keeps m2e's own default (no arg at all).
+    let mut cfg = server("jdtls");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &Settings::default());
+    assert!(cfg.args.iter().all(|a| !a.contains("maven.repo.local")));
+}
+
 #[test]
 fn rust_analyzer_check_command_and_toolchain() {
     if cfg!(windows) {