private String nextUnquotedValue() throws IOException {
    long i = source.indexOfElement(UNQUOTED_STRING_TERMINALS);
    return i != -1 ? buffer.readUtf8(i) : buffer.readUtf8();
  }
Returns an unquoted value as a string.
lottie/src/main/java/com/airbnb/lottie/parser/moshi/JsonUtf8Reader.java