I first ran into this with a trait that had a property of type List<String>, where GRECLIPSE was treating the property as type List<E> and producing errors, but I had trouble replicating it. However, this replicates what appears to be the same problem:

@Grab('com.google.guava:guava:29.0-jre')
import com.google.common.reflect.TypeToken

class Generics {
  private static final TypeToken<List<String>> LIST_STRING =
    new TypeToken<List<String>>() {}
    // ^ Type mismatch: cannot convert from new TypeToken<Object>(){} to TypeToken
}

This error is present in 4.8.0.v202211162249-e2206 (e4.24), and I think it was present in the nightly from Tuesday. It might be in Groovy itself, but groovyc 4.0.6 has no trouble with it.