text: public Pair<String,String> splitExtensionField(String defaultField,String field) {int indexOf = field.indexOf(this.extensionFieldDelimiter);if (indexOf < 0)return new Pair<>(field, null);final String indexField = indexOf == 0 ? defaultField : field.substring(0,indexOf);final String extensionKey = field.substring(indexOf + 1);return new Pair<>(indexField, extensionKey);}