fix: resolve mypy errors and None concatenation bug in JavaSupport

- Fix TypeError in _build_runtime_map when test_function_name is None
- Add missing abstract method stubs (find_references, extract_calling_function_source, load_coverage, setup_test_config)
- Fix Language import to come from language_enum instead of base (which doesn't re-export it)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: github-actions[bot]

codeflash/languages/java/support.py

@@ -9,7 +9,8 @@
 import logging
 from typing import TYPE_CHECKING, Any
 
-from codeflash.languages.base import Language, LanguageSupport
+from codeflash.languages.base import LanguageSupport
+from codeflash.languages.language_enum import Language
 from codeflash.languages.java.build_tools import find_test_root
 from codeflash.languages.java.comparator import compare_test_results as _compare_test_results
 from codeflash.languages.java.concurrency_analyzer import analyze_function_concurrency
@@ -344,6 +345,8 @@ def add_runtime_comments_to_generated_tests(
     def _build_runtime_map(self, inv_id_runtimes: dict[InvocationId, list[int]]) -> dict[str, int]:
         unique_inv_ids: dict[str, int] = {}
         for inv_id, runtimes in inv_id_runtimes.items():
+            if not inv_id.test_function_name:
+                continue
             test_qualified_name = (
                 inv_id.test_class_name + "." + inv_id.test_function_name
                 if inv_id.test_class_name
@@ -370,6 +373,33 @@ def compare_test_results(
         """Compare test results between original and candidate code."""
         return _compare_test_results(original_results_path, candidate_results_path, project_root=project_root)
 
+    # === Reference Finding ===
+
+    def find_references(
+        self,
+        function: FunctionToOptimize,
+        project_root: Path,
+        tests_root: Path | None = None,
+        max_files: int = 500,
+    ) -> list[Any]:
+        return []
+
+    def extract_calling_function_source(self, source_code: str, function_name: str, ref_line: int) -> str | None:
+        return None
+
+    def load_coverage(
+        self,
+        coverage_database_file: Path,
+        function_name: str,
+        code_context: Any,
+        source_file: Path,
+        coverage_config_file: Path | None = None,
+    ) -> None:
+        return None
+
+    def setup_test_config(self, test_cfg: Any, file_path: Path) -> None:
+        return None
+
     # === Configuration ===
 
     def adjust_test_config_for_discovery(self, test_cfg: Any) -> None: