public Builder setSourceRoot(
              int index, java.lang.String value) {
            if (value == null) { throw new NullPointerException(); }
            ensureSourceRootIsMutable();
            sourceRoot_.set(index, value);
            bitField0_ |= 0x00000002;
            onChanged();
            return this;
          }
public Builder setSourceRoot(
              int index, java.lang.String value)