Read custom Attributes of DNG Artifact using OSLC
One answer
I assume you're using Eclipse Lyo.
The extended Properties in a Lyo Object are originized in a Map. To get the value of a custom attribute, you new to know the URI defined in the Artifact Attributes.
The you can simply fetch with the following statement
requirement.getExtendedProperties().get(new QName("http://your.namespace/definition","attributeName"));
Please notice, that's highly recommended to set the URI value for a custom attribute, otherwise DNG set's this value on it's own and this results in a DNG specific namespace and the custom attribute's unique identifier.