@java.lang.Override
      public Builder mergeFrom(
          com.google.protobuf.CodedInputStream input,
          com.google.protobuf.ExtensionRegistryLite extensionRegistry)
          throws java.io.IOException {
        if (extensionRegistry == null) {
          throw new java.lang.NullPointerException();
        }
        try {
          boolean done = false;
          while (!done) {
            int tag = input.readTag();
            switch (tag) {
              case 0:
                done = true;
                break;
              case 10:
                {
                  image_ = input.readStringRequireUtf8();
                  bitField0_ |= 0x00000001;
                  break;
                } // case 10
              case 18:
                {
                  java.lang.String s = input.readStringRequireUtf8();
                  ensureCommandIsMutable();
                  command_.add(s);
                  break;
                } // case 18
              case 26:
                {
                  java.lang.String s = input.readStringRequireUtf8();
                  ensureArgsIsMutable();
                  args_.add(s);
                  break;
                } // case 26
              case 34:
                {
                  com.google.protobuf.MapEntry<java.lang.String, java.lang.String> env__ =
                      input.readMessage(
                          EnvDefaultEntryHolder.defaultEntry.getParserForType(), extensionRegistry);
                  internalGetMutableEnv().getMutableMap().put(env__.getKey(), env__.getValue());
                  bitField0_ |= 0x00000008;
                  break;
                } // case 34
              case 42:
                {
                  workingDir_ = input.readStringRequireUtf8();
                  bitField0_ |= 0x00000010;
                  break;
                } // case 42
              case 48:
                {
                  runAsUser_ = input.readInt32();
                  bitField0_ |= 0x00000020;
                  break;
                } // case 48
              default:
                {
                  if (!super.parseUnknownField(input, extensionRegistry, tag)) {
                    done = true; // was an endgroup tag
                  }
                  break;
                } // default:
            } // switch (tag)
          } // while (!done)
        } catch (com.google.protobuf.InvalidProtocolBufferException e) {
          throw e.unwrapIOException();
        } finally {
          onChanged();
        } // finally
        return this;
      }
<pre>
A Docker container.
</pre>

Protobuf type {@code google.cloud.workstations.v1beta.WorkstationConfig.Container}
java-workstations/proto-google-cloud-workstations-v1beta/src/main/java/com/google/cloud/workstations/v1beta/WorkstationConfig.java