code: public boolean isValid() {
  		if (this.cpuCores >= 0 && this.heapMemoryInMB >= 0 && this.directMemoryInMB >= 0 &&
  				this.nativeMemoryInMB >= 0 && this.stateSizeInMB >= 0) {
  			for (Resource resource : extendedResources.values()) {
  				if (resource.getValue() < 0) {
  					return false;
  				}
  			}
  			return true;
  		} else {
  			return false;
  		}
  	}
docs: Check whether all the field values are valid.
  
  @return True if all the values are equal or greater than 0, otherwise false.