QuerydslPredicateBuilder#getPredicate uses a function called isSingleElementCollectionWithoutText to filter out all single element collection values that are null/empty string/string with nothing but whitespace.
Sometimes you do want to use values that are just an empty string or a string with nothing but whitespaces.
One workaround is to add the same value twice, so it's not regarded as a single element collection. In this case, the value doesn't get filtered out.
For example, when using the QueryDSL Web Support, GETting "/notes?name=%20" will end up returning all notes since "name= " gets dropped by QuerydslPredicateBuilder#isSingleElementCollectionWithoutText.
"/notes?name=%20&name=%20" will end up returning only the notes with " " as name.