build.xml has a dependency for an old hadoop-core version (1.0.3). This is likely needed for some Hadoop compatibility code under `src/java/org/apache/cassandra/hadoop`. Since 1.0.3 was released in 2012, its dependencies are very old; in particular it depends on "jackson-mapper-asl" 1.0.1 (from 2009!).
An earlier issue
CASSANDRA-15867 referenced this dependency as well (but did not actually remove it for some reason, which marked as resolved).
Although `hadoop-core` dependency is marked as "provided" (and should then not be included in distributed version) it seems best to avoid downloading it during build to "build/lib/jars". This can be done by adding 2 exclusions for "hadoop-core" and "hadoop-minicluster" dependencies in build.xml.
I will provide a patch.
I also tried updating "hadoop-core" to the latest public version (1.2.1), which would have upgraded jackson-mapper-asl to 1.8.8, but that breaks the build due to some other version incompatibility (asm, possibly). If anyone wants to tackle that issue it could be a good follow-up task; "hadoop-core" itself has been moved to "hadoop-client" it seems (and there's "hadoop-commons" too... confusing).