void removeAllFields() {
    if(this.ifFalse != null) {
      this.ifFalse.removeAllFields();
    }
    this.ifTrue.removeAllFields();
  }
Merge the variable data from 2 maps.
@param mapTo The first map to merge. Will be mutated.
              The result will be stored in this map.
@param map2 The second map to merge. Will not be mutated. Nullable.
src/org/jetbrains/java/decompiler/modules/decompiler/sforms/VarMapHolder.java