private boolean isGoodMagic(int magic) {
    return magic == CLASS_FILE_MAGIC;
  }
Sees if the .class file header magic has the good value.

@param magic the value of a classfile "magic" field
@return true if the magic is valid
android/android_framework/dex-maker/src/main/java/com/android/dx/cf/direct/DirectClassFile.java