Does the retention of occupancy risk preclude the recognition of a gain on sale of property?

 Entity A is a food and household goods group, which has undergone a significant restructure and disposed of non-core activities. As part of the restructure entity A sold a building to entity B in20X2. The building is located in a prime commercial location and entity B intends to refurbish it and lease it out as an investment property. The remaining expected life of the building is30 years. The local property market experienced commercial occupancy rates of70% in20X2 and property analysts predict that this rate will continue. However, to encourage B to buy the property, entity A has agreed to guarantee a minimum of90 % occupancy of the building in20X3 and20X4.