In some cases you may want to manipulate the payload of a human task of an OPBM or BPEL process instance using JAXB. An example would be when you are using some other framework than ADF Faces for creating the UI, and you want to work with Java objects instead of manipulating XML programatically.
To do so with JDeveloper, you can generate the JAXB content model by right clicking the xsd and choose "Generate JAXB x.x Content Model".
Be aware that you must do this using the human-task-specific payload, and not the xsd that was used to define the variable that gets passed into that human task, otherwise to your sad surprise you will get all kind XML validation issues when trying to push the data back to the process. Fortunately on its turn the xsd of the human-task-specific payload imports the original xsd, so when the original xsd changes, the human task specific payload automatically changes with it. You still have to regenerate the JAXB content model to let it reflect the changes.
The following picture shows the OrderCreationPayload.xsd of an OrderCreation human task. It imports an Order.xsd. The JAXB content model has to be generated using the OrderCreationPayload instead of the Order.