### Question:
UserResource { static Response validateAtMostOneAdminRole(final Collection<String> roles) { Collection<String> adminRoles = new ArrayList<String>(Arrays.asList(ADMIN_ROLES)); adminRoles.retainAll(roles); if (adminRoles.size() > 1) { return composeForbiddenResponse("You cannot assign more than one admin role to a user"); } return null; }  @POST @RightsAllowed({Right.CRUD_LEA_ADMIN, Right.CRUD_SEA_ADMIN, Right.CRUD_SLC_OPERATOR, Right.CRUD_SANDBOX_ADMIN, Right.CRUD_SANDBOX_SLC_OPERATOR }) final Response create(final User newUser); @GET @RightsAllowed({Right.CRUD_LEA_ADMIN, Right.CRUD_SEA_ADMIN, Right.CRUD_SLC_OPERATOR, Right.CRUD_SANDBOX_ADMIN, Right.CRUD_SANDBOX_SLC_OPERATOR }) final Response readAll(); @PUT @RightsAllowed({Right.CRUD_LEA_ADMIN, Right.CRUD_SEA_ADMIN, Right.CRUD_SLC_OPERATOR, Right.CRUD_SANDBOX_ADMIN, Right.CRUD_SANDBOX_SLC_OPERATOR }) final Response update(final User updateUser); @DELETE @Path("{uid}") @RightsAllowed({Right.CRUD_LEA_ADMIN, Right.CRUD_SEA_ADMIN, Right.CRUD_SLC_OPERATOR, Right.CRUD_SANDBOX_ADMIN, Right.CRUD_SANDBOX_SLC_OPERATOR }) final Response delete(@PathParam("uid") final String uid); @GET @Path("edorgs") @RightsAllowed({Right.CRUD_LEA_ADMIN, Right.CRUD_SEA_ADMIN, Right.CRUD_SLC_OPERATOR, Right.CRUD_SANDBOX_ADMIN, Right.CRUD_SANDBOX_SLC_OPERATOR }) final Response getEdOrgs(); void setRealm(String realm);  }### Answer:
@Test public void testValidateAtMostOneAdminRole() { assertNull(UserResource.validateAtMostOneAdminRole(Arrays.asList(new String[] {}))); assertNull(UserResource.validateAtMostOneAdminRole(Arrays .asList(new String[] { RoleInitializer.INGESTION_USER }))); assertNull(UserResource .validateAtMostOneAdminRole(Arrays.asList(new String[] { RoleInitializer.SLC_OPERATOR }))); assertNotNull(UserResource.validateAtMostOneAdminRole(Arrays.asList(new String[] { RoleInitializer.SLC_OPERATOR, RoleInitializer.LEA_ADMINISTRATOR }))); assertNull(UserResource.validateAtMostOneAdminRole(Arrays.asList(new String[] { RoleInitializer.LEA_ADMINISTRATOR, RoleInitializer.LEA_ADMINISTRATOR }))); }