1. A method in a data processing system for securing a server runtime environment, comprising: generating by a server runtime environment executing in a server device a first unique identifier at startup of the server runtime environment to uniquely identify the server runtime environment executing in the server device; storing the first unique identifier that uniquely identifies the server runtime environment in a private location in the server runtime environment; receiving a request to instantiate a first user credential object that represents a first user identity; inserting the first unique identifier that uniquely identifies the server runtime environment in a private field in the first user credential object; receiving a request to instantiate a second user credential object that represents a second user identity; and inserting the first unique identifier that uniquely identifies the server runtime environment in a private field in the second user credential object such that the first user credential object and the second user credential object include the same first unique identifier.