code: @Implementation
    protected final Uri insert(Uri url, ContentValues values) {
      ContentProvider provider = getProvider(url);
      ContentValues valuesCopy = (values == null) ? null : new ContentValues(values);
      InsertStatement insertStatement = new InsertStatement(url, provider, valuesCopy);
      statements.add(insertStatement);
      insertStatements.add(insertStatement);
  
      if (provider != null) {
        return provider.insert(url, values);
      } else {
        return Uri.parse(url.toString() + "/" + ++nextDatabaseIdForInserts);
      }
    }
docs: If a {@link ContentProvider} is registered for the given {@link Uri}, its {@link
  ContentProvider#insert(Uri, ContentValues)} method will be invoked.
  
  <p>Tests can verify that this method was called using {@link #getStatements()} or {@link
  #getInsertStatements()}.
  
  <p>If no appropriate {@link ContentProvider} is found, no action will be taken and a {@link
  Uri} including the incremented value set with {@link #setNextDatabaseIdForInserts(int)} will
  returned.