### Question:
TokenResponse implements Persistable { @Override public String persist() { return new Gson().toJson(this); } TokenResponse(); @NonNull String getAccessToken(); @NonNull String getTokenType(); @NonNull String getExpiresIn(); @NonNull String getScope(); String getRefreshToken(); String getIdToken(); void setCreationTime(long creationTime); long getExpiresAt(); @NonNull @Override String getKey(); @Override String persist(); static final Persistable.Restore<TokenResponse> RESTORE; }### Answer:
@Test public void persist() { String json = mToken.persist(); TokenResponse tokenResponse = new Gson().fromJson(json, TokenResponse.class); assertEquals(tokenResponse.persist(), json); }