isCompleteMPUInProgress(params, log, cb) {
        assert.strictEqual(typeof params, 'object');
        assert.strictEqual(typeof params.bucketName, 'string');
        assert.strictEqual(typeof params.objectKey, 'string');
        assert.strictEqual(typeof params.uploadId, 'string');
        assert.strictEqual(typeof params.splitter, 'string');

        const mpuBucketName = `${constants.mpuBucketPrefix}${params.bucketName}`;
        const splitter = params.splitter;
        const mpuOverviewKey =
            `overview${splitter}${params.objectKey}${splitter}${params.uploadId}`;
        return metadata.getObjectMD(mpuBucketName, mpuOverviewKey, {}, log,
            (err, res) => {
                if (err) {
                    log.error('error getting the overview object from mpu bucket', {
                        error: err,
                        method: 'services.isCompleteMPUInProgress',
                        params,
                    });
                    return cb(err);
                }
                return cb(null, Boolean(res.completeInProgress));
            });
    }
Returns if a CompleteMPU operation is in progress for this
object, by looking at the `completeInProgress` flag stored in
the overview key

@param {object} params - params object
@param {string} params.bucketName - bucket name where object should be stored
@param {string} params.objectKey - object key
@param {string} params.uploadId - upload ID
@param {string} params.splitter - splitter for this overview key
@param {object} log - request logger instance
@param {function} cb - callback(err, {bool} completeInProgress)
@return {undefined}