@Nullable
    protected Predicate createFilter(QueryMetadata metadata) {
        Predicate filter;
        if (!metadata.getJoins().isEmpty()) {
            filter = ExpressionUtils.allOf(metadata.getWhere(), createJoinFilter(metadata));
        } else {
            filter = metadata.getWhere();
        }
        return filter;
    }
Define a constraint for an embedded object

@param collection collection
@param target target
@return builder
querydsl-mongodb/src/main/java/com/querydsl/mongodb/document/AbstractMongodbQuery.java