A ValueExtractor may use a custom argument if it is specified in the query.
The custom argument may be passed within the square brackets located after the name of the custom attribute,
e.g., customAttribute[argument].
Let's have a look at the following query: currency[incoming] == EUR
The currency is a custom attribute that uses a com.test.CurrencyExtractor for extraction.
The string incoming is an argument that will be passed to the ArgumentParser during the extraction.
The parser will parse the string according to the parser's custom logic and it will return a parsed object.
The parsed object may be a single object, array, collection, or any arbitrary object.
It is up to the ValueExtractor's implementor to understand the semantics of the parsed argument object.
For now it is not possible to register a custom ArgumentParser, thus a default parser is used.
It follows a pass-through semantic, which means that the string located in the square brackets is passed "as is" to
the ValueExtractor.extract() method.
Please note that using square brackets within the argument string is not allowed.