Don't assume that libraries are built with Maven

In the report for grpc-auth at https://storage.googleapis.com/cloud-opensource-java-dashboard/dashboard/target/dashboard/io.grpc_grpc-auth_1.15.1.html , it makes a recommendation to "Add this dependency element to the pom.xml for io.grpc:grpc-auth:1.15.1". However, grpc is built with gradle, so this advice cannot be followed.