public void setFilter(String filter) throws IllegalArgumentException {
        if (StringUtils.isBlank(filter)) {
            this.filter = ClassPathFilter.TRUE;
        } else {
            this.filter = new Parser().parse(filter);
        }
    }
public void setFilter ( String filter ) throws IllegalArgumentException { if ( StringUtils . isBlank ( filter ) ) { this . filter = ClassPathFilter . TRUE ; } else { this . filter = new Parser ( ) . parse ( filter ) ; } }
Set the class filter. Only classes that pass the filter will be included.
By default the filter accepts all classes. Passing a null or null length
string will result in all classes passing the test.

@param filter
The string representation of the filter. May be null.
@throws IllegalArgumentException if the filter can not be parsed.