fix: include default deprecation reason in the composed supergraph

`@deprecated` reason used to be optional in the past and as such it was omitted from the supergraph schema. [Reason is no longer optional](graphql/graphql-spec#1040) so we should always include it (even if it is a default).

Author: dariuszkuc

composition-js/src/__tests__/compose.test.ts

@@ -54,7 +54,7 @@ describe('composition', () => {
         type T @key(fields: "k") {
           k: ID
           a: Int
-          b: String
+          b: String @deprecated
         }
 
         enum E {
@@ -66,6 +66,7 @@ describe('composition', () => {
 
     const result = composeAsFed2Subgraphs([subgraph1, subgraph2]);
     assertCompositionSuccess(result);
+    console.log(`${result.supergraphSdl}`);
 
     expect(result.supergraphSdl).toMatchString(`
       schema
@@ -149,7 +150,7 @@ describe('composition', () => {
       {
         k: ID
         a: Int @join__field(graph: SUBGRAPH2)
-        b: String @join__field(graph: SUBGRAPH2)
+        b: String @join__field(graph: SUBGRAPH2) @deprecated(reason: "No longer supported")
       }
 
       union U
@@ -177,7 +178,7 @@ describe('composition', () => {
       type T {
         k: ID
         a: Int
-        b: String
+        b: String @deprecated(reason: "No longer supported")
       }
 
       union U = S | T

internals-js/src/definitions.ts

@@ -3260,6 +3260,12 @@ export class Directive<
     const args = entries.length == 0 ? '' : '(' + entries.map(([n, v]) => `${n}: ${valueToString(v, this.argumentType(n))}`).join(', ') + ')';
     return `@${this.name}${args}`;
   }
+
+  toStringWithDefaultValues(): string {
+    const entries = Object.entries(this.arguments(true)).filter(([_, v]) => v !== undefined);
+    const args = entries.length == 0 ? '' : '(' + entries.map(([n, v]) => `${n}: ${valueToString(v, this.argumentType(n))}`).join(', ') + ')';
+    return `@${this.name}${args}`;
+  }
 }
 
 /**

internals-js/src/print.ts

@@ -24,6 +24,7 @@ import {
 } from "./definitions";
 import { assert } from "./utils";
 import { valueToString } from "./values";
+import { GraphQLDeprecatedDirective } from 'graphql/type';
 
 export type PrintOptions = {
   indentString: string;
@@ -235,7 +236,13 @@ function printAppliedDirectives(
     return "";
   }
   const joinStr = onNewLines ? '\n' + options.indentString : ' ';
-  const directives = appliedDirectives.map(d => d.toString()).join(joinStr);
+  const directives = appliedDirectives.map(d => {
+    if (GraphQLDeprecatedDirective.name === d.name) {
+      return d.toStringWithDefaultValues();
+    } else {
+      return d.toString();
+    }
+  }).join(joinStr);
   return onNewLines ? '\n' + options.indentString + directives + (endWithNewLine ? '\n' : '') : ' ' + directives;
 }