public NumberExpression<Integer> indexOf(Expression<String> str) {
        return Expressions.numberOperation(Integer.class, Ops.INDEX_OF, mixin, str);
    }
Create a {@code this.indexOf(str)} expression

<p>Get the index of the given substring in this String</p>

@param str string
@return this.indexOf(str)
@see java.lang.String#indexOf(String)
querydsl-core/src/main/java/com/querydsl/core/types/dsl/StringExpression.java