presto-main/src/main/java/io/prestosql/operator/scalar/JsonExtract.java/ObjectFieldJsonExtractor/ObjectFieldJsonExtractor
class ObjectFieldJsonExtractor:        public ObjectFieldJsonExtractor(String fieldName, JsonExtractor<? extends T> delegate, boolean exceptionOnOutOfBounds)
        {
            this.fieldName = new SerializedString(requireNonNull(fieldName, "fieldName is null"));
            this.delegate = requireNonNull(delegate, "delegate is null");
            this.exceptionOnOutOfBounds = exceptionOnOutOfBounds;
            this.index = tryParseInt(fieldName, -1);
        }