EPMOSDU-1179 Fixed empty bucket name

Description:

Fixed empty bucket name. Example:

unsignedUrl = https://dev.com/osduarea/a420/test.txt
transferProtocol = https://dev.com
String[] pathParts = ["", "/osduarea/a420/test.txt"]
String[] objectKeyParts = ["", "osduarea", "a420", "test.txt"]
.bucketName(objectKeyParts[0])

For this case, bucketName will be empty.

Changes include:

• Refactor (a non-breaking change that improves code maintainability).

Changes in:

• GCP