Add support for optional methods

Summary:
This diff adds an optional property.

#Facebook
Following this doc: https://our.intern.facebook.com/intern/wiki/React_Native/rctexport-interface-support/?vitals_event=wiki_click_navigation_link
I suppose it's vital to support this property as well. However i don't know if it's really useful, so thus I made a separated diff for it.

Reviewed By: TheSavior

Differential Revision: D16121408

fbshipit-source-id: 15491575e999ee4fcddfd176f52d927789458061

packages/react-native-codegen/src/CodegenSchema.js

@@ -172,6 +172,7 @@ export type FunctionTypeAnnotation = $ReadOnly<{|
   type: 'FunctionTypeAnnotation',
   params: $ReadOnlyArray<FunctionTypeAnnotationParam>,
   returnTypeAnnotation: FunctionTypeAnnotationReturn,
+  optional: boolean,
 |}>;
 
 export type MethodTypeShape = $ReadOnly<{|

packages/react-native-codegen/src/parsers/flow/__test_fixtures__/fixtures.js

@@ -51,7 +51,7 @@ import type {TurboModule} from '../RCTExport';
 import * as TurboModuleRegistry from '../TurboModuleRegistry';
 
 export interface Spec extends TurboModule {
-  +passBool: (arg: boolean) => void;
+  +passBool?: (arg: boolean) => void;
   +passNumber: (arg: number) => void;
   +passString: (arg: string) => void;
 }

packages/react-native-codegen/src/parsers/flow/__tests__/__snapshots__/parser-test.js.snap

@@ -3336,6 +3336,7 @@ Object {
             Object {
               "name": "getArray",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3374,6 +3375,7 @@ Object {
             Object {
               "name": "getArray",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3412,6 +3414,7 @@ Object {
             Object {
               "name": "passBool",
               "typeAnnotation": Object {
+                "optional": true,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3429,6 +3432,7 @@ Object {
             Object {
               "name": "passNumber",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3446,6 +3450,7 @@ Object {
             Object {
               "name": "passString",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3478,6 +3483,7 @@ Object {
             Object {
               "name": "getArray",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3575,6 +3581,7 @@ Object {
             Object {
               "name": "getNumber",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [
                   Object {
                     "name": "arg",
@@ -3592,6 +3599,7 @@ Object {
             Object {
               "name": "getVoid",
               "typeAnnotation": Object {
+                "optional": false,
                 "params": Array [],
                 "returnTypeAnnotation": Object {
                   "type": "VoidTypeAnnotation",

packages/react-native-codegen/src/parsers/flow/methods.js

@@ -222,6 +222,7 @@ function buildMethodSchema(
       type: 'FunctionTypeAnnotation',
       returnTypeAnnotation,
       params,
+      optional: property.optional,
     },
   };
 }