compute equals/hashCode correctly even in case of null values
compute equals/hashCode correctly even in case of null values

xph906/SootNew,anddann/soot,anddann/soot,xph906/SootNew,plast-lab/soot,mbenz89/soot,plast-lab/soot,cfallin/soot,xph906/SootNew,mbenz89/soot,mbenz89/soot,plast-lab/soot,anddann/soot,anddann/soot,cfallin/soot,cfallin/soot,xph906/SootNew,mbenz89/soot,cfallin/soot