in core/src/main/scala/com/gu/marley/AvroSerialisable.scala [111:116]
def findCompanionOfThisOrParentWithMethod(method: String): Option[c.universe.Symbol] =
(for {
c <- typ.baseClasses
t = c.asType.toType
list <- t.companion.decls.find(_.name == TermName(method))
} yield list).headOption