Service generation fails with an NPE when `@deprecated` is present on a field

[zetcco]

Consider the following schema with @deprecated on the products: [Product!]! field on the Query type,

schema
  @link(url: "https://specs.apollo.dev/link/v1.0")
  @link(url: "https://specs.apollo.dev/join/v0.3", for: EXECUTION)
{
  query: Query
}

directive @join__enumValue(graph: join__Graph!) repeatable on ENUM_VALUE

directive @join__field(graph: join__Graph, requires: join__FieldSet, provides: join__FieldSet, type: String, external: Boolean, override: String, usedOverridden: Boolean) repeatable on FIELD_DEFINITION | INPUT_FIELD_DEFINITION

directive @join__graph(name: String!, url: String!) on ENUM_VALUE

directive @join__implements(graph: join__Graph!, interface: String!) repeatable on OBJECT | INTERFACE

directive @join__type(graph: join__Graph!, key: join__FieldSet, extension: Boolean! = false, resolvable: Boolean! = true, isInterfaceObject: Boolean! = false) repeatable on OBJECT | INTERFACE | UNION | ENUM | INPUT_OBJECT | SCALAR

directive @join__unionMember(graph: join__Graph!, member: String!) repeatable on UNION

directive @link(url: String, as: String, for: link__Purpose, import: [link__Import]) repeatable on SCHEMA

scalar join__FieldSet

enum join__Graph {
  PRODUCTS @join__graph(name: "products", url: "http://localhost:9091")
}

scalar link__Import

enum link__Purpose {
  """
  `SECURITY` features provide metadata necessary to securely resolve fields.
  """
  SECURITY

  """
  `EXECUTION` features provide metadata necessary for operation execution.
  """
  EXECUTION
}

type Product
  @join__type(graph: PRODUCTS, key: "id")
{
  id: ID!
  name: String!
  description: String!
  price: Float!
}

type Query
  @join__type(graph: PRODUCTS)
{
  products: [Product!]! @deprecated
  product(id: ID!): Product
}

Then running the following command,

bal run .\graphql_federation_gateway.jar -CsupergraphPath="supergraphs/0.1.3.graphql" -CoutputPath="generated_gateway"

Results in,

error: java.lang.NullPointerException {"message":"Cannot invoke "graphql.schema.GraphQLAppliedDirectiveArgument.getArgumentValue()" because the return value of "graphql.schema.GraphQLAppliedDirective.getArgument(String)" is null"}
        at xlibb.graphql_federation_gateway.0:generateGateway(main.bal:25)
           xlibb.graphql_federation_gateway.0:main(main.bal:16)