Avro.JsonHelper.GetOptionalString C# (CSharp) Method

        public static string GetOptionalString(JToken j, string field)
        {
            if (log.IsDebugEnabled) log.DebugFormat("getOptionalString(JToken, string) - field = {1}, j = {0}", j, field);
            if (null == j) throw new ArgumentNullException("j", "j cannot be null.");
            if (string.IsNullOrEmpty(field)) throw new ArgumentNullException("field", "field cannot be null.");

            JToken child = j[field];
            if (log.IsDebugEnabled) log.DebugFormat("getOptionalString(JToken, string) - child = {0}", child);
            if (null == child) return null;

            if (child.Type == JTokenType.String)
            {
                string value = child.ToString();
                return value.Trim('\"');
            }
            throw new SchemaParseException("Field " + field + " is not a string");
        }

        /// <summary>
        /// Static function to return new instance of EnumSchema
        /// </summary>
        /// <param name="jtok">JSON object for enum schema</param>
        /// <param name="names">list of named schema already parsed in</param>
        /// <param name="encspace">enclosing namespace for the enum schema</param>
        /// <returns>new instance of enum schema</returns>
        internal static EnumSchema NewInstance(JToken jtok, PropertyMap props, SchemaNames names, string encspace)
        {
            SchemaName name    = NamedSchema.GetName(jtok, encspace);
            var        aliases = NamedSchema.GetAliases(jtok, name.Space, name.EncSpace);

            JArray jsymbols = jtok["symbols"] as JArray;

            if (null == jsymbols)
            {
                throw new SchemaParseException("Enum has no symbols: " + name);
            }

            List <string>             symbols   = new List <string>();
            IDictionary <string, int> symbolMap = new Dictionary <string, int>();
            int i = 0;

            foreach (JValue jsymbol in jsymbols)
            {
                string s = (string)jsymbol.Value;
                if (symbolMap.ContainsKey(s))
                {
                    throw new SchemaParseException("Duplicate symbol: " + s);
                }

                symbolMap[s] = i++;
                symbols.Add(s);
            }
            return(new EnumSchema(name, aliases, symbols, symbolMap, props, names,
                                  JsonHelper.GetOptionalString(jtok, "doc")));
        }