Declared license not collected

I collect `pkg:maven/com.carrotsearch/hppc@0.7.1` using the collect/index_packages API endpoint.
The declared license is never filled in, even though the parent POM has it. The `other_license_expression` is populated though when doing a look up on the "enhanced" endpoint.

Here are the URLs:
- https://repo1.maven.org/maven2/com/carrotsearch/hppc/0.7.1/
- https://repo1.maven.org/maven2/com/carrotsearch/hppc/0.7.1/hppc-0.7.1.pom (no license)
- https://repo1.maven.org/maven2/com/carrotsearch/hppc-parent/0.7.1/hppc-parent-0.7.1.pom (parent with license)
- https://repo1.maven.org/maven2/org/sonatype/oss/oss-parent/9/oss-parent-9.pom (parent's parent that MUST be ignored)