Google Cloud BOM (Maven artifact ID com.google.cloud:google-cloud-bom) lists
Google Cloud Java client libraries. The Google Cloud Libraries BOM imports
Google Cloud BOM.
Google Cloud recommends Java users to use the Libraries BOM (Maven artifact ID
com.google.cloud:libraries-bom), instead of Google Cloud BOM.
It's because the Libraries BOM sets the consistent versions of libraries
including the core Java libraries.
Cloud's documentation and samples also use the Libraries BOM.