java: add tests for thread safe initialisation

Co-authored-by: Raúl Pardo <raul.pardo@protonmail.com>

java/ql/test/query-tests/ThreadSafe/examples/ThreadSafeInitializers.java

@@ -0,0 +1,55 @@
+package examples;
+
+import java.util.Map;
+import java.util.Set;
+import java.util.HashMap;
+import java.util.Collections;
+import java.util.concurrent.ConcurrentHashMap;
+
+@ThreadSafe
+public class ThreadSafeInitializers {
+
+    private int y;
+    private final Map<Integer, Integer> sync_map;
+    private final Map<Integer, Integer> sync_map_initialised = Collections.synchronizedMap(new HashMap<Integer, Integer>());
+
+    
+    private final Map<String, String> cmap;
+    private final Map<String, String> cmap_initialised = new ConcurrentHashMap();
+    private final Set<Integer> set;
+    private final Set<Integer> set_initialised = ConcurrentHashMap.newKeySet();
+    
+    public ThreadSafeInitializers() {
+        sync_map = Collections.synchronizedMap(new HashMap<Integer, Integer>());
+        cmap = new ConcurrentHashMap();
+        set = ConcurrentHashMap.newKeySet();
+    }
+
+    public void sync_map_put(Integer i, Integer v) {
+        sync_map.put(i,v); // $ SPURIOUS: Alert
+    }
+
+    public void sync_map_initialised_put(Integer i, Integer v) {
+        sync_map_initialised.put(i,v);
+    }
+
+    public void cmap_put(String s1, String s2) {
+        cmap.put(s1, s2); // $ SPURIOUS: Alert
+    }
+
+    public void cmap_initialised_put(String s1, String s2) {
+        cmap_initialised.put(s1, s2);
+    }
+
+    public void setY(int y) {
+        this.y = y; // $ Alert
+    }
+
+    public void set_add(Integer i) {
+        set.add(i); // $ SPURIOUS: Alert
+    }
+
+    public void set_initialised_add(Integer i) {
+        set_initialised.add(i);
+    }
+}