Remove unneeded implementation

src/main/java/dev/lukebemish/codecextras/mutable/DataElement.java

@@ -5,33 +5,4 @@ public interface DataElement<T> {
 	T get();
 	boolean dirty();
 	void setDirty(boolean dirty);
-
-	class Simple<T> implements DataElement<T> {
-		public Simple(T defaultValue) {
-			this.value = defaultValue;
-		}
-
-		private volatile T value;
-		private volatile boolean dirty;
-
-		@Override
-		public synchronized void set(T t) {
-			this.value = t;
-		}
-
-		@Override
-		public T get() {
-			return value;
-		}
-
-		@Override
-		public boolean dirty() {
-			return dirty;
-		}
-
-		@Override
-		public void setDirty(boolean dirty) {
-			this.dirty = dirty;
-		}
-	}
 }