@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:
              {
                name_ = input.readStringRequireUtf8();
                bitField0_ |= 0x00000001;
                break;
              } // case 10
            case 18:
              {
                spanId_ = input.readStringRequireUtf8();
                bitField0_ |= 0x00000002;
                break;
              } // case 18
            case 26:
              {
                parentSpanId_ = input.readStringRequireUtf8();
                bitField0_ |= 0x00000004;
                break;
              } // case 26
            case 34:
              {
                input.readMessage(getDisplayNameFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000008;
                break;
              } // case 34
            case 42:
              {
                input.readMessage(getStartTimeFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000010;
                break;
              } // case 42
            case 50:
              {
                input.readMessage(getEndTimeFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000020;
                break;
              } // case 50
            case 58:
              {
                input.readMessage(getAttributesFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000040;
                break;
              } // case 58
            case 66:
              {
                input.readMessage(getStackTraceFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000080;
                break;
              } // case 66
            case 74:
              {
                input.readMessage(getTimeEventsFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000100;
                break;
              } // case 74
            case 82:
              {
                input.readMessage(getLinksFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000200;
                break;
              } // case 82
            case 90:
              {
                input.readMessage(getStatusFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000400;
                break;
              } // case 90
            case 98:
              {
                input.readMessage(
                    getSameProcessAsParentSpanFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000800;
                break;
              } // case 98
            case 106:
              {
                input.readMessage(getChildSpanCountFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00001000;
                break;
              } // case 106
            case 112:
              {
                spanKind_ = input.readEnum();
                bitField0_ |= 0x00002000;
                break;
              } // case 112
            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 span represents a single operation within a trace. Spans can be
nested to form a trace tree. Often, a trace contains a root span
that describes the end-to-end latency, and one or more subspans for
its sub-operations.

A trace can also contain multiple root spans, or none at all.
Spans do not need to be contiguous. There might be
gaps or overlaps between spans in a trace.
</pre>

Protobuf type {@code google.devtools.cloudtrace.v2.Span}
java-trace/proto-google-cloud-trace-v2/src/main/java/com/google/devtools/cloudtrace/v2/Span.java