public NumberExpression<T> floor() {
        if (floor == null) {
            floor = Expressions.numberOperation(getType(), MathOps.FLOOR, mixin);
        }
        return floor;
    }
Create a {@code floor(this)} expression

<p>Returns the largest (closest to positive infinity)
{@code double} value that is less than or equal to the
argument and is equal to a mathematical integer.</p>

@return floor(this)
@see java.lang.Math#floor(double)
querydsl-core/src/main/java/com/querydsl/core/types/dsl/NumberExpression.java