openrtb-core/src/main/java/com/google/openrtb/json/OpenRtbNativeJsonWriter.java
public String writeNativeRequest(NativeRequest req) throws IOException {
    try (StringWriter writer = new StringWriter()) {
      writeNativeRequest(req, writer);
      return writer.toString();
    }
  }
public String writeNativeRequest(NativeRequest req) throws IOException {
    try (StringWriter writer = new StringWriter()) {
      writeNativeRequest(req, writer);
      return writer.toString();
    }
  }
Serializes a {@link NativeRequest} to JSON, returned as a {@code String}.