feat(generator): update protoc to v3.15.3 (#898)

* chore: update protobuf v3.15.3

This release makes --experimental_allow_proto3_optional no longer necessary.

PiperOrigin-RevId: 359781040

Source-Author: Google APIs <noreply@google.com>
Source-Date: Fri Feb 26 09:59:49 2021 -0800
Source-Repo: googleapis/googleapis
Source-Sha: f6dd7e47620566925a4b3f1ce029e74e1b2f2516
Source-Link: googleapis/googleapis@f6dd7e4

* Update clirr-ignored-differences.xml

Co-authored-by: Stephanie Wang <stephaniewang526@users.noreply.github.com>

proto-google-cloud-bigquerystorage-v1alpha2/clirr-ignored-differences.xml

@@ -2,24 +2,9 @@
 <!-- see http://www.mojohaus.org/clirr-maven-plugin/examples/ignored-differences.html -->
 <differences>
     <!--TODO: To be removed-->
-    <difference>
-        <className>com/google/cloud/bigquery/storage/v1alpha2/Storage$AppendRowsRequestOrBuilder</className>
-        <method>boolean getIgnoreUnknownFields()</method>
-        <differenceType>7012</differenceType>
-    </difference>
-    <difference>
-        <className>com/google/cloud/bigquery/storage/v1alpha2/Storage$AppendRowsResponseOrBuilder</className>
-        <method>com.google.cloud.bigquery.storage.v1alpha2.Table$TableSchema getUpdatedSchema()</method>
-        <differenceType>7012</differenceType>
-    </difference>
-    <difference>
-        <className>com/google/cloud/bigquery/storage/v1alpha2/Storage$AppendRowsResponseOrBuilder</className>
-        <method>com.google.cloud.bigquery.storage.v1alpha2.Table$TableSchemaOrBuilder getUpdatedSchemaOrBuilder()</method>
-        <differenceType>7012</differenceType>
-    </difference>
     <difference>
         <className>com/google/cloud/bigquery/storage/v1alpha2/Storage$AppendRowsResponseOrBuilder</className>
-        <method>boolean hasUpdatedSchema()</method>
+        <method>boolean hasOffset()</method>
         <differenceType>7012</differenceType>
     </difference>
 </differences>

proto-google-cloud-bigquerystorage-v1alpha2/src/main/java/com/google/cloud/bigquery/storage/v1alpha2/Storage.java

@@ -3788,6 +3788,18 @@ public com.google.protobuf.Parser<AppendRowsRequest> getParserForType() {
       // @@protoc_insertion_point(interface_extends:google.cloud.bigquery.storage.v1alpha2.AppendRowsResponse)
       com.google.protobuf.MessageOrBuilder {
 
+    /**
+     *
+     *
+     * <pre>
+     * The row offset at which the last append occurred.
+     * </pre>
+     *
+     * <code>int64 offset = 1;</code>
+     *
+     * @return Whether the offset field is set.
+     */
+    boolean hasOffset();
     /**
      *
      *
@@ -4054,6 +4066,21 @@ public ResponseCase getResponseCase() {
     }
 
     public static final int OFFSET_FIELD_NUMBER = 1;
+    /**
+     *
+     *
+     * <pre>
+     * The row offset at which the last append occurred.
+     * </pre>
+     *
+     * <code>int64 offset = 1;</code>
+     *
+     * @return Whether the offset field is set.
+     */
+    @java.lang.Override
+    public boolean hasOffset() {
+      return responseCase_ == 1;
+    }
     /**
      *
      *
@@ -4610,6 +4637,20 @@ public Builder clearResponse() {
         return this;
       }
 
+      /**
+       *
+       *
+       * <pre>
+       * The row offset at which the last append occurred.
+       * </pre>
+       *
+       * <code>int64 offset = 1;</code>
+       *
+       * @return Whether the offset field is set.
+       */
+      public boolean hasOffset() {
+        return responseCase_ == 1;
+      }
       /**
        *
        *

synth.metadata

@@ -11,39 +11,39 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquerystorage.git",
-        "sha": "3a942cda09b263d910454b584273b45eee03406c"
+        "sha": "d211c76dff747121d4560b55818c10bf595ef1c3"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "af8f71dae961ee036a0ac52a1965270149a6b2c9",
-        "internalRef": "358516065"
+        "sha": "f6dd7e47620566925a4b3f1ce029e74e1b2f2516",
+        "internalRef": "359781040"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "af8f71dae961ee036a0ac52a1965270149a6b2c9",
-        "internalRef": "358516065"
+        "sha": "f6dd7e47620566925a4b3f1ce029e74e1b2f2516",
+        "internalRef": "359781040"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "af8f71dae961ee036a0ac52a1965270149a6b2c9",
-        "internalRef": "358516065"
+        "sha": "f6dd7e47620566925a4b3f1ce029e74e1b2f2516",
+        "internalRef": "359781040"
       }
     },
     {
       "git": {
         "name": "googleapis",
         "remote": "https://github.com/googleapis/googleapis.git",
-        "sha": "af8f71dae961ee036a0ac52a1965270149a6b2c9",
-        "internalRef": "358516065"
+        "sha": "f6dd7e47620566925a4b3f1ce029e74e1b2f2516",
+        "internalRef": "359781040"
       }
     },
     {