update: implement remove method in DefaultLRUCache for cache entry removal

Author: FarhanAnjum-opti

core-api/src/main/java/com/optimizely/ab/internal/Cache.java

@@ -22,4 +22,5 @@ public interface Cache<T> {
     void save(String key, T value);
     T lookup(String key);
     void reset();
+    void remove(String key);
 }

core-api/src/main/java/com/optimizely/ab/internal/DefaultLRUCache.java

@@ -94,6 +94,19 @@ public void reset() {
         }
     }
 
+    public void remove(String key) {
+        if (maxSize == 0) {
+            // Cache is disabled when maxSize = 0
+            return;
+        }
+        lock.lock();
+        try {
+            linkedHashMap.remove(key);
+        } finally {
+            lock.unlock();
+        }
+    }
+
     private class CacheEntity {
         public T value;
         public Long timestamp;