System.getProperty("os.arch") reports process architecture, not OS.

In a 32-bit process running on a 64-bit OS, System.getProperty("os.arch") will report the architecture of the process. This is different to that of the actual OS, and contradicts the documentation.

The use of that architecture value is usually to be reported in some user interface, so although not key to any JVM function, it can be misleading, and the value could be used to attempt to locate architecture-specific libraries.