yaml extension parser rejects valid yaml (e.g. with description field)

[benbellick]

E.g.

%YAML 1.2
---
urn: extension:test:custom_extensions
types:
  - name: "customType1"
    description: >-
      some description

Fails parsing:

    java.lang.IllegalStateException: com.fasterxml.jackson.databind.exc.UnrecognizedPropertyException: Unrecognized field "description" (class io.substrait.extension.ImmutableSimpleExtension$Type$Json), not marked as ignorable (3 known properties: "urn", "name", "structure"])
     at [Source: (StringReader); line: 8, column: 1] (through reference chain: io.substrait.extension.ImmutableSimpleExtension$ExtensionSignatures$Json["types"]->java.util.ArrayList[0]->io.substrait.extension.ImmutableSimpleExtension$Type$Json["description"])

There may be more valid things that aren't accounted for.