diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index c5cbc5540..92394b1e4 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -11,7 +11,7 @@ jobs:
       matrix:
         node: [8, 10, 12, 13]
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:
           node-version: ${{ matrix.node }}
@@ -30,7 +30,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:
           node-version: 12
@@ -39,7 +39,7 @@ jobs:
   docs:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:
           node-version: 12
@@ -48,7 +48,7 @@ jobs:
   coverage:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - uses: actions/setup-node@v1
         with:
           node-version: 13
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e50e0775b..136e1da88 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,21 @@
 
 [1]: https://www.npmjs.com/package/@google-cloud/firestore?activeTab=versions
 
+### [3.7.3](https://www.github.com/googleapis/nodejs-firestore/compare/v3.7.2...v3.7.3) (2020-03-31)
+
+
+### Bug Fixes
+
+* support array of references for IN queries ([#993](https://www.github.com/googleapis/nodejs-firestore/issues/993)) ([a6d8fe0](https://www.github.com/googleapis/nodejs-firestore/commit/a6d8fe061fcfe0fde7a4fa023b2ec454e2adb432))
+
+### [3.7.2](https://www.github.com/googleapis/nodejs-firestore/compare/v3.7.1...v3.7.2) (2020-03-25)
+
+
+### Bug Fixes
+
+* fix flaky contention test ([#979](https://www.github.com/googleapis/nodejs-firestore/issues/979)) ([f294998](https://www.github.com/googleapis/nodejs-firestore/commit/f294998daab77a0a51c81265945e28eec34db186))
+* fix: use Random Number from `crypto` to generate AutoId ([05b3363](https://www.github.com/googleapis/nodejs-firestore/commit/ce6ea390f2fffcbe796ba1c5b040ee02452e287a))
+
 ### [3.7.1](https://www.github.com/googleapis/nodejs-firestore/compare/v3.7.0...v3.7.1) (2020-03-16)
 
 
diff --git a/README.md b/README.md
index e2381d368..ba729e8a8 100644
--- a/README.md
+++ b/README.md
@@ -113,6 +113,27 @@ has instructions for running the samples.
 The [Cloud Firestore Node.js Client API Reference][client-docs] documentation
 also contains samples.
 
+## Supported Node.js Versions
+
+Our client libraries follow the [Node.js release schedule](https://nodejs.org/en/about/releases/).
+Libraries are compatible with all current _active_ and _maintenance_ versions of
+Node.js.
+
+Client libraries targetting some end-of-life versions of Node.js are available, and
+can be installed via npm [dist-tags](https://docs.npmjs.com/cli/dist-tag).
+The dist-tags follow the naming convention `legacy-(version)`.
+
+_Legacy Node.js versions are supported as a best effort:_
+
+* Legacy versions will not be tested in continuous integration.
+* Some security patches may not be able to be backported.
+* Dependencies will not be kept up-to-date, and features will not be backported.
+
+#### Legacy tags available
+
+* `legacy-8`: install client libraries from this dist-tag for versions
+  compatible with Node.js 8.
+
 ## Versioning
 
 This library follows [Semantic Versioning](http://semver.org/).
diff --git a/dev/src/document.ts b/dev/src/document.ts
index 7bb020398..6ce7ccb99 100644
--- a/dev/src/document.ts
+++ b/dev/src/document.ts
@@ -505,26 +505,6 @@ export class DocumentSnapshot<T = DocumentData> {
 export class QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot<
   T
 > {
-  /**
-   * @hideconstructor
-   *
-   * @param ref The reference to the document.
-   * @param fieldsProto The fields of the Firestore `Document` Protobuf backing
-   * this document.
-   * @param readTime The time when this snapshot was read.
-   * @param createTime The time when the document was created.
-   * @param updateTime The time when the document was last updated.
-   */
-  constructor(
-    ref: DocumentReference<T>,
-    fieldsProto: ApiMapValue,
-    readTime: Timestamp,
-    createTime: Timestamp,
-    updateTime: Timestamp
-  ) {
-    super(ref, fieldsProto, readTime, createTime, updateTime);
-  }
-
   /**
    * The time the document was created.
    *
diff --git a/dev/src/reference.ts b/dev/src/reference.ts
index 40f60f522..7d46f0d16 100644
--- a/dev/src/reference.ts
+++ b/dev/src/reference.ts
@@ -1240,7 +1240,23 @@ export class Query<T = DocumentData> {
     const path = FieldPath.fromArgument(fieldPath);
 
     if (FieldPath.documentId().isEqual(path)) {
-      value = this.validateReference(value);
+      if (opStr === 'array-contains' || opStr === 'array-contains-any') {
+        throw new Error(
+          `Invalid Query. You can't perform '${opStr}' ` +
+            'queries on FieldPath.documentId().'
+        );
+      }
+
+      if (opStr === 'in') {
+        if (!Array.isArray(value) || value.length === 0) {
+          throw new Error(
+            `Invalid Query. A non-empty array is required for '${opStr}' filters.`
+          );
+        }
+        value = value.map(el => this.validateReference(el));
+      } else {
+        value = this.validateReference(value);
+      }
     }
 
     const fieldFilter = new FieldFilter(
@@ -1595,7 +1611,7 @@ export class Query<T = DocumentData> {
     } else {
       throw new Error(
         'The corresponding value for FieldPath.documentId() must be a ' +
-          'string or a DocumentReference.'
+          `string or a DocumentReference, but was "${val}".`
       );
     }
 
diff --git a/dev/src/util.ts b/dev/src/util.ts
index d7a690ce7..d04253699 100644
--- a/dev/src/util.ts
+++ b/dev/src/util.ts
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+import {randomBytes} from 'crypto';
 import {GoogleError, ServiceConfig, Status} from 'google-gax';
 
 import {DocumentData} from './types';
@@ -52,8 +53,17 @@ export function autoId(): string {
   const chars =
     'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
   let autoId = '';
-  for (let i = 0; i < 20; i++) {
-    autoId += chars.charAt(Math.floor(Math.random() * chars.length));
+  while (autoId.length < 20) {
+    const bytes = randomBytes(40);
+    bytes.forEach(b => {
+      // Length of `chars` is 62. We only take bytes between 0 and 62*4-1
+      // (both inclusive). The value is then evenly mapped to indices of `char`
+      // via a modulo operation.
+      const maxValue = 62 * 4 - 1;
+      if (autoId.length < 20 && b <= maxValue) {
+        autoId += chars.charAt(b % 62);
+      }
+    });
   }
   return autoId;
 }
diff --git a/dev/src/v1/firestore_admin_client.ts b/dev/src/v1/firestore_admin_client.ts
index 0787ec706..96c5f19f6 100644
--- a/dev/src/v1/firestore_admin_client.ts
+++ b/dev/src/v1/firestore_admin_client.ts
@@ -1,4 +1,4 @@
-// Copyright 2019 Google LLC
+// Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -42,7 +42,12 @@ const version = require('../../../package.json').version;
  * @memberof v1
  */
 export class FirestoreAdminClient {
-  private _descriptors: Descriptors = {page: {}, stream: {}, longrunning: {}};
+  private _descriptors: Descriptors = {
+    page: {},
+    stream: {},
+    longrunning: {},
+    batching: {},
+  };
   private _innerApiCalls: {[name: string]: Function};
   private _pathTemplates: {[name: string]: gax.PathTemplate};
   private _terminated = false;
@@ -307,7 +312,8 @@ export class FirestoreAdminClient {
           if (this._terminated) {
             return Promise.reject('The client has already been closed.');
           }
-          return stub[methodName].apply(stub, args);
+          const func = stub[methodName];
+          return func.apply(stub, args);
         },
         (err: Error | null | undefined) => () => {
           throw err;
diff --git a/dev/src/v1/firestore_client.ts b/dev/src/v1/firestore_client.ts
index 5a6339187..4a0630f95 100644
--- a/dev/src/v1/firestore_client.ts
+++ b/dev/src/v1/firestore_client.ts
@@ -1,4 +1,4 @@
-// Copyright 2019 Google LLC
+// Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -47,7 +47,12 @@ const version = require('../../../package.json').version;
  * @memberof v1
  */
 export class FirestoreClient {
-  private _descriptors: Descriptors = {page: {}, stream: {}, longrunning: {}};
+  private _descriptors: Descriptors = {
+    page: {},
+    stream: {},
+    longrunning: {},
+    batching: {},
+  };
   private _innerApiCalls: {[name: string]: Function};
   private _terminated = false;
   private _opts: ClientOptions;
@@ -250,7 +255,8 @@ export class FirestoreClient {
           if (this._terminated) {
             return Promise.reject('The client has already been closed.');
           }
-          return stub[methodName].apply(stub, args);
+          const func = stub[methodName];
+          return func.apply(stub, args);
         },
         (err: Error | null | undefined) => () => {
           throw err;
diff --git a/dev/src/v1beta1/firestore_client.ts b/dev/src/v1beta1/firestore_client.ts
index 938b1e5db..b330e4e56 100644
--- a/dev/src/v1beta1/firestore_client.ts
+++ b/dev/src/v1beta1/firestore_client.ts
@@ -1,4 +1,4 @@
-// Copyright 2019 Google LLC
+// Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -55,7 +55,12 @@ const version = require('../../../package.json').version;
  * @memberof v1beta1
  */
 export class FirestoreClient {
-  private _descriptors: Descriptors = {page: {}, stream: {}, longrunning: {}};
+  private _descriptors: Descriptors = {
+    page: {},
+    stream: {},
+    longrunning: {},
+    batching: {},
+  };
   private _innerApiCalls: {[name: string]: Function};
   private _terminated = false;
   private _opts: ClientOptions;
@@ -258,7 +263,8 @@ export class FirestoreClient {
           if (this._terminated) {
             return Promise.reject('The client has already been closed.');
           }
-          return stub[methodName].apply(stub, args);
+          const func = stub[methodName];
+          return func.apply(stub, args);
         },
         (err: Error | null | undefined) => () => {
           throw err;
diff --git a/dev/synth.metadata b/dev/synth.metadata
index 22062172c..fb2024a6f 100644
--- a/dev/synth.metadata
+++ b/dev/synth.metadata
@@ -1,19 +1,19 @@
 {
-  "updateTime": "2020-03-05T23:07:35.336516Z",
+  "updateTime": "2020-03-22T11:28:16.621427Z",
   "sources": [
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "f0b581b5bdf803e45201ecdb3688b60e381628a8",
-        "internalRef": "299181282"
+        "sha": "0be7105dc52590fa9a24e784052298ae37ce53aa",
+        "internalRef": "302154871"
       }
     },
     {
-      "template": {
-        "name": "node_library",
-        "origin": "synthtool.gcp",
-        "version": "2020.2.4"
+      "git": {
+        "name": "synthtool",
+        "remote": "https://github.com/googleapis/synthtool.git",
+        "sha": "7e98e1609c91082f4eeb63b530c6468aefd18cfd"
       }
     }
   ],
diff --git a/dev/system-test/firestore.ts b/dev/system-test/firestore.ts
index 02ba04186..b5e6c4bb6 100644
--- a/dev/system-test/firestore.ts
+++ b/dev/system-test/firestore.ts
@@ -18,6 +18,7 @@ import * as chaiAsPromised from 'chai-as-promised';
 import {
   CollectionReference,
   DocumentData,
+  DocumentReference,
   DocumentSnapshot,
   FieldPath,
   FieldValue,
@@ -1079,9 +1080,17 @@ describe('Query class', () => {
       });
   };
 
-  function addDocs(...data: DocumentData[]): Promise<WriteResult[]> {
+  async function addDocs(
+    ...docs: DocumentData[]
+  ): Promise<DocumentReference[]> {
     let id = 0; // Guarantees consistent ordering for the first documents
-    return Promise.all(data.map(d => randomCol.doc('' + id++).set(d)));
+    const refs: DocumentReference[] = [];
+    for (const doc of docs) {
+      const ref = randomCol.doc('doc' + id++);
+      await ref.set(doc);
+      refs.push(ref);
+    }
+    return refs;
   }
 
   function expectDocs(result: QuerySnapshot, ...data: DocumentData[]) {
@@ -1171,7 +1180,7 @@ describe('Query class', () => {
       });
   });
 
-  it('supports in', async () => {
+  it('supports "in"', async () => {
     await addDocs(
       {zip: 98101},
       {zip: 91102},
@@ -1184,6 +1193,14 @@ describe('Query class', () => {
     expectDocs(res, {zip: 98101}, {zip: 98103});
   });
 
+  it('supports "in" with document ID array', async () => {
+    const refs = await addDocs({count: 1}, {count: 2}, {count: 3});
+    const res = await randomCol
+      .where(FieldPath.documentId(), 'in', [refs[0].id, refs[1]])
+      .get();
+    expectDocs(res, {count: 1}, {count: 2});
+  });
+
   it('supports array-contains-any', async () => {
     await addDocs(
       {array: [42]},
diff --git a/dev/test/gapic-firestore-v1.ts b/dev/test/gapic-firestore-v1.ts
index 6e5ba0e20..7e884a8d2 100644
--- a/dev/test/gapic-firestore-v1.ts
+++ b/dev/test/gapic-firestore-v1.ts
@@ -1,4 +1,4 @@
-// Copyright 2019 Google LLC
+// Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/dev/test/gapic-firestore-v1beta1.ts b/dev/test/gapic-firestore-v1beta1.ts
index 61472d1dc..bd1169dbc 100644
--- a/dev/test/gapic-firestore-v1beta1.ts
+++ b/dev/test/gapic-firestore-v1beta1.ts
@@ -1,4 +1,4 @@
-// Copyright 2019 Google LLC
+// Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/dev/test/gapic-firestore_admin-v1.ts b/dev/test/gapic-firestore_admin-v1.ts
index c4f322a73..179089643 100644
--- a/dev/test/gapic-firestore_admin-v1.ts
+++ b/dev/test/gapic-firestore_admin-v1.ts
@@ -1,4 +1,4 @@
-// Copyright 2019 Google LLC
+// Copyright 2020 Google LLC
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
diff --git a/dev/test/query.ts b/dev/test/query.ts
index 12f6a84e3..33cdf4b72 100644
--- a/dev/test/query.ts
+++ b/dev/test/query.ts
@@ -847,6 +847,77 @@ describe('where() interface', () => {
     });
   });
 
+  it('supports reference array for IN queries', () => {
+    const overrides: ApiOverride = {
+      runQuery: request => {
+        queryEquals(
+          request,
+          fieldFilters('__name__', 'IN', {
+            arrayValue: {
+              values: [
+                {
+                  referenceValue: `projects/${PROJECT_ID}/databases/(default)/documents/collectionId/foo`,
+                },
+                {
+                  referenceValue: `projects/${PROJECT_ID}/databases/(default)/documents/collectionId/bar`,
+                },
+              ],
+            },
+          })
+        );
+
+        return stream();
+      },
+    };
+
+    return createInstance(overrides).then(firestore => {
+      const collection = firestore.collection('collectionId');
+      const query = collection.where(FieldPath.documentId(), 'in', [
+        'foo',
+        collection.doc('bar'),
+      ]);
+      return query.get();
+    });
+  });
+
+  it('validates references for IN queries', () => {
+    const query = firestore.collection('collectionId');
+
+    expect(() => {
+      query.where(FieldPath.documentId(), 'in', ['foo', 42]);
+    }).to.throw(
+      'The corresponding value for FieldPath.documentId() must be a string or a DocumentReference, but was "42".'
+    );
+
+    expect(() => {
+      query.where(FieldPath.documentId(), 'in', 42);
+    }).to.throw(
+      "Invalid Query. A non-empty array is required for 'in' filters."
+    );
+
+    expect(() => {
+      query.where(FieldPath.documentId(), 'in', []);
+    }).to.throw(
+      "Invalid Query. A non-empty array is required for 'in' filters."
+    );
+  });
+
+  it('validates query operator for FieldPath.document()', () => {
+    const query = firestore.collection('collectionId');
+
+    expect(() => {
+      query.where(FieldPath.documentId(), 'array-contains', query.doc());
+    }).to.throw(
+      "Invalid Query. You can't perform 'array-contains' queries on FieldPath.documentId()."
+    );
+
+    expect(() => {
+      query.where(FieldPath.documentId(), 'array-contains-any', query.doc());
+    }).to.throw(
+      "Invalid Query. You can't perform 'array-contains-any' queries on FieldPath.documentId()."
+    );
+  });
+
   it('rejects custom objects for field paths', () => {
     expect(() => {
       let query: Query = firestore.collection('collectionId');
@@ -1511,7 +1582,7 @@ describe('startAt() interface', () => {
     expect(() => {
       query.orderBy(FieldPath.documentId()).startAt(42);
     }).to.throw(
-      'The corresponding value for FieldPath.documentId() must be a string or a DocumentReference.'
+      'The corresponding value for FieldPath.documentId() must be a string or a DocumentReference, but was "42".'
     );
 
     expect(() => {
diff --git a/package.json b/package.json
index 129d92386..feed6f49d 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@google-cloud/firestore",
   "description": "Firestore Client Library for Node.js",
-  "version": "3.7.1",
+  "version": "3.7.3",
   "license": "Apache-2.0",
   "author": "Google Inc.",
   "engines": {
diff --git a/samples/package.json b/samples/package.json
index d2e8e617e..238dae4b3 100644
--- a/samples/package.json
+++ b/samples/package.json
@@ -11,7 +11,7 @@
     "test": "mocha --timeout 600000"
   },
   "dependencies": {
-    "@google-cloud/firestore": "^3.7.1"
+    "@google-cloud/firestore": "^3.7.3"
   },
   "devDependencies": {
     "chai": "^4.2.0",