presto-main/src/main/java/io/prestosql/operator/scalar/JsonToRowCast.java/JsonToRowCast/JsonToRowCast
class JsonToRowCast:    private JsonToRowCast()
    {
        super(OperatorType.CAST,
                ImmutableList.of(
                        // this is technically a recursive constraint for cast, but TypeRegistry.canCast has explicit handling for json to row cast
                        new TypeVariableConstraint("T", false, false, "row", ImmutableSet.of(), ImmutableSet.of(JSON.getTypeSignature()))),
                ImmutableList.of(),
                new TypeSignature("T"),
                ImmutableList.of(JSON.getTypeSignature()),
                true);
    }