driver-core/src/main/com/mongodb/operation/CommandOperationHelper.java
private static <T> T executeCommand(final String database, final BsonDocument command,
                                        final FieldNameValidator fieldNameValidator, final Decoder<T> decoder,
                                        final ConnectionSource source, final Connection connection,
                                        final ReadPreference readPreference) {
        return executeCommand(database, command, fieldNameValidator, decoder, source, connection,
                readPreference, new IdentityReadTransformer<T>(), source.getSessionContext());
    }
private static <T> T executeCommand(final String database, final BsonDocument command,
                                        final FieldNameValidator fieldNameValidator, final Decoder<T> decoder,
                                        final ConnectionSource source, final Connection connection,
                                        final ReadPreference readPreference) {
        return executeCommand(database, command, fieldNameValidator, decoder, source, connection,
                readPreference, new IdentityReadTransformer<T>(), source.getSessionContext());
    }
/* Private Read Connection Source Helpers