openrtb-core/src/main/java/com/google/openrtb/json/OpenRtbJsonUtils.java
public static void writeLongs(String fieldName, List<Long> data, JsonGenerator gen)
      throws IOException {
    if (!data.isEmpty()) {
      gen.writeArrayFieldStart(fieldName);
      for (long d : data) {
        writeLong(d, gen);
      }
      gen.writeEndArray();
    }
  }
public static void writeLongs(String fieldName, List<Long> data, JsonGenerator gen)
      throws IOException {
    if (!data.isEmpty()) {
      gen.writeArrayFieldStart(fieldName);
      for (long d : data) {
        writeLong(d, gen);
      }
      gen.writeEndArray();
    }
  }
Writes a long array if not empty, using quotes for values that are too big.

@see #writeLong(long, JsonGenerator)