public SsaBasicBlock getPrimarySuccessor() {
    if (primarySuccessor < 0) {
      return null;
    } else {
      return parent.getBlocks().get(primarySuccessor);
    }
  }
@return {@code null-ok;} the primary successor block or {@code null} if there is none
android/android_framework/dex-maker/src/main/java/com/android/dx/ssa/SsaBasicBlock.java