In http://opensource.box.com/box-java-sdk/javadoc/com/box/sdk/BoxUser.html#getAllEnterpriseOrExternalUsers(com.box.sdk.BoxAPIConnection,%20java.lang.String,%20java.lang.String...) you can specify a filterTerm for box.com get users call.
What format can this filterTerm take?
Iterable<com.box.sdk.BoxUser.Info> users = BoxUser.getAllEnterpriseUsers(api, "App");
Iterable<com.box.sdk.BoxUser.Info> users = BoxUser.getAllEnterpriseUsers(api, "Ken");
Iterable<com.box.sdk.BoxUser.Info> users = BoxUser.getAllEnterpriseUsers(api, "[email protected]");