List of labels; nonconfigurable; default is the package's default_package_metadata

A list of labels that are associated metadata about this target. Typically, the labels are simple rules that return a provider of constant values. Rules and aspects may use these labels to perform some additional analysis on the build graph.

The canonical use case is that of rules_license. For that use case, package_metadata and default_package_metadata is used to attach information about a package's licence or version to targets. An aspect applied to a top-level binary can be used to gather those and produce compliance reports.