Some maven artifacts do not have any sha1 sums computed but rather md5
ones so handle these edge cases to still check download integrity of
jar files.
See https://repo1.maven.org/maven2/org/jetbrains/kotlin/kotlin-test-annotations-common/1.5.30-M1/ for instance.
Depends on D8839
Fixes SWH-LOADER-CORE-1BP.