Section 32. In construing sections thirty, thirty-one, thirty-three and thirty-four the words ”laborers, workmen and mechanics” shall be deemed to include engineers and also janitors, custodians and other employees doing similar work in schools or other public buildings under the jurisdiction of any department, commission or board of the commonwealth or of any county, city or town, and a threat of loss of employment or a threat to obstruct or prevent the obtaining of employment or to refrain from employing in the future shall be considered to be ”requiring” within the meaning of sections thirty, thirty-one and thirty-four.