The JCR specification does not support empty properties:

• only the setProperty() method exists
• setting a property to null removes it

But the content API has both createNodeData() and setNodeData() methods but since they use JCR properties they behave which I consider being wrong:

• createNodeData(name) will not fail if a node data already exist
• setNodeData(name) will not fail it the node data doesn't exist yet
• getNodeData(name) will never fail but return an nodeData where isExists() might return false
• createNodeData(name, type) creates a property by setting an empty string value (null would not create a property) no matter what type you specify

So there are two solutions possible:

A) differentiate the creation and setting

• means throw exception if you are doing wrong

B) drop the explicit creation (as in JCR)

I am very much in favor of B) and would like to deprecate all createNodeData() methods