Typical (string) length

The typicalLength() element indicates the typical length of a string parameter. It is ignored for parameters of other types.

The information is intended as a hint to the UI to determine the space that should be given to render a particular string parameter.

For example:

public class Customer {

    public Customer updateName(
                @Parameter(maxLength=30)
                @ParameterLayout(
                    typicalLength=20
                )
                final String firstName,
                @Parameter(maxLength=30)
                @ParameterLayout(
                    typicalLength=20
                )
                final String lastName) {
        // ...
    }

    // ...
}
All that said, the Web UI (Wicket viewer) uses the maximum space available for all fields, so in effect ignores this element.