AbstractCredentials implements Credentials { @NotNull public String getUserId() { return userId; } AbstractCredentials(@NotNull String userId); @NotNull String getUserId(); void setAttribute(@NotNull String name, @Nullable Object value); @Nullable Object getAttribute(@NotNull String name); void removeAttribute(@NotNull String name); @NotNull Map<String,Object> getAttributes(); void setAttributes(@NotNull Map<String,Object> attributes);  }
@Test public void testGetUserId() { assertEquals(USER_ID, credentials.getUserId()); }