Cannot filter entity queries by fields mapped as xsd:string

[claudiu-cristea]

Cannot filter entity queries by fields mapped as xsd:string

[idimopoulos]

This actually works fine on a normal case. The use case that does fail, is when there is a condition
$query->condition('field_name', '') where it does not translate as null or adds an empty string and the final query is malformed as the result is
?subject ?predicate without an ?object in the end.