Added a expected withdrawals API interface

packages/api/src/beacon/routes/builder.ts

@@ -0,0 +1,65 @@
+import {Slot, ValidatorIndex, WithdrawalIndex} from "@lodestar/types";
+import {ReturnTypes, RoutesData, Schema, sameType, ReqSerializers} from "../../utils/index.js";
+import {HttpStatusCode} from "../../utils/client/httpStatusCode.js";
+import {ApiClientResponse} from "../../interfaces.js";
+import {StateId, ExecutionOptimistic} from "./beacon/state.js";
+
+export type ExpectedWithdrawals = {
+  index: WithdrawalIndex;
+  validatorIndex: ValidatorIndex;
+  address: string;
+  amount: number;
+};
+
+// See /packages/api/src/routes/index.ts for reasoning and instructions to add new routes
+
+export type Api = {
+  getExpectedWithdrawals(
+    stateId: StateId,
+    proposalSlot?: Slot | undefined
+  ): Promise<
+    ApiClientResponse<
+      {
+        [HttpStatusCode.OK]: {
+          executionOptimistic: ExecutionOptimistic;
+          data: ExpectedWithdrawals[];
+        };
+      },
+      HttpStatusCode.NOT_FOUND | HttpStatusCode.BAD_REQUEST
+    >
+  >;
+};
+/**
+ * Define javascript values for each route
+ */
+export const routesData: RoutesData<Api> = {
+  getExpectedWithdrawals: {url: "/eth/v1/builder/states/{state_id}/expected_withdrawals", method: "GET"},
+};
+
+/* eslint-disable @typescript-eslint/naming-convention */
+export type ReqTypes = {
+  getExpectedWithdrawals: {params: {state_id: StateId}; query: {proposal_slot?: Slot | undefined}};
+};
+
+export function getReqSerializers(): ReqSerializers<Api, ReqTypes> {
+  return {
+    getExpectedWithdrawals: {
+      writeReq: (state_id, proposal_slot) => ({
+        params: {state_id},
+        query: {proposal_slot},
+      }),
+      parseReq: ({params, query}) => [params.state_id, query.proposal_slot],
+      schema: {
+        params: {state_id: Schema.StringRequired},
+        query: {proposal_slot: Schema.Uint},
+      },
+    },
+  };
+}
+
+export function getReturnTypes(): ReturnTypes<Api> {
+  return {
+    // Just sent the proof JSON as-is
+    getExpectedWithdrawals: sameType(),
+  };
+}