[Minor] fixed compiler warnings

src/main/java/ch/eitchnet/xmlpers/api/IoMode.java

@@ -50,10 +50,18 @@ public enum IoMode {
 		}
 	};
 
+	/**
+	 * @param ctx
+	 * @param fileIo
+	 */
 	public <T> void write(PersistenceContext<T> ctx, FileIo fileIo) {
 		throw new UnsupportedOperationException("Override me!"); //$NON-NLS-1$
 	}
 
+	/**
+	 * @param ctx
+	 * @param fileIo
+	 */
 	public <T> void read(PersistenceContext<T> ctx, FileIo fileIo) {
 		throw new UnsupportedOperationException("Override me!"); //$NON-NLS-1$
 	}

src/main/java/ch/eitchnet/xmlpers/api/TransactionCloseStrategy.java

@@ -15,6 +15,9 @@ public enum TransactionCloseStrategy {
 		}
 	};
 
+	/**
+	 * @param tx
+	 */
 	public void close(PersistenceTransaction tx) {
 		throw new UnsupportedOperationException("Override in enum!"); //$NON-NLS-1$
 	}

src/main/java/ch/eitchnet/xmlpers/objref/IdOfSubTypeRef.java

@@ -22,6 +22,7 @@ public class IdOfSubTypeRef extends ObjectRef {
 		this.id = id;
 	}
 
+	@Override
 	public String getType() {
 		return this.type;
 	}

src/main/java/ch/eitchnet/xmlpers/objref/IdOfTypeRef.java

@@ -20,6 +20,7 @@ public class IdOfTypeRef extends ObjectRef {
 		this.id = id;
 	}
 
+	@Override
 	public String getType() {
 		return this.type;
 	}

src/main/java/ch/eitchnet/xmlpers/objref/SubTypeRef.java

@@ -18,6 +18,7 @@ public class SubTypeRef extends ObjectRef {
 		this.subType = subType;
 	}
 
+	@Override
 	public String getType() {
 		return this.type;
 	}

src/main/java/ch/eitchnet/xmlpers/objref/TypeRef.java

@@ -16,6 +16,7 @@ public class TypeRef extends ObjectRef {
 		this.type = type;
 	}
 
+	@Override
 	public String getType() {
 		return this.type;
 	}

src/test/java/ch/eitchnet/xmlpers/test/FileDaoTest.java

@@ -80,7 +80,7 @@ public class FileDaoTest extends AbstractPersistenceTest {
 		try (PersistenceTransaction tx = new DefaultPersistenceTransaction(this.realm, VERBOSE)) {
 			FileDao fileDao = new FileDao(tx, this.pathBuilder, VERBOSE);
 			tx.setIoMode(IoMode.SAX);
-			testCrud(tx, this.realm.getCtxFactoryDelegator(), fileDao);
+			testCrud(this.realm.getCtxFactoryDelegator(), fileDao);
 		}
 	}
 
@@ -90,12 +90,11 @@ public class FileDaoTest extends AbstractPersistenceTest {
 		try (PersistenceTransaction tx = new DefaultPersistenceTransaction(this.realm, VERBOSE)) {
 			FileDao fileDao = new FileDao(tx, this.pathBuilder, VERBOSE);
 			tx.setIoMode(IoMode.DOM);
-			testCrud(tx, this.realm.getCtxFactoryDelegator(), fileDao);
+			testCrud(this.realm.getCtxFactoryDelegator(), fileDao);
 		}
 	}
 
-	private void testCrud(PersistenceTransaction tx, PersistenceContextFactoryDelegator ctxFactoryDelegator,
-			FileDao fileDao) {
+	private void testCrud(PersistenceContextFactoryDelegator ctxFactoryDelegator, FileDao fileDao) {
 
 		Resource resource = createResource();
 		assertResource(resource);