FULL PRODUCT VERSION :
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows 10

EXTRA RELEVANT SYSTEM CONFIGURATION :
Running on compatibility mode (for example, Windows 7)

A DESCRIPTION OF THE PROBLEM :
Try this below code in a number of Java version / vendor combinations in Windows 10 OS, after each of the 'java' executbale made compatible with Windows 7.


C:\foo>cat OSN.java
public class OSN {
  public static void main(String args[]) {
    System.out.println(System.getProperty("os.name"));
  }
}

C:\foo>java -version
java version "1.8.0"
Java(TM) SE Runtime Environment (build pwa6480sr3-20160428_01(SR3))
IBM J9 VM (build 2.8, JRE 1.8.0 Windows 7 amd64-64 Compressed References 20160427_301573 (JIT enabled, AOT enabled)
J9VM - R28_Java8_SR3_20160427_1620_B301573
JIT  - tr.r14.java.green_20160329_114288
GC   - R28_Java8_SR3_20160427_1620_B301573_CMPRSS
J9CL - 20160427_301573)
JCL - 20160421_01 based on Oracle jdk8u91-b14

C:\foo>java OSN
Windows 7

C:\foo>..\java7\bin\java -version
java version "1.7.0_80"
Java(TM) SE Runtime Environment (build 1.7.0_80-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.80-b11, mixed mode)

C:\foo>..\java7\bin\java OSN
Windows 7

C:\foo>..\java8\jdk1.8.0\bin\java -version
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)

C:\foo>..\java8\jdk1.8.0\bin\java OSN
Windows 7

C:\foo>..\java8_u51\bin\java -version
java version "1.8.0_51"
Java(TM) SE Runtime Environment (build 1.8.0_51-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.51-b03, mixed mode)

C:\foo>..\java8_u51\bin\java OSN
Windows 7

C:\foo>"C:\Program Files\Java\jre1.8.0_131\bin\java.exe" -version
java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)

C:\foo>"C:\Program Files\Java\jre1.8.0_131\bin\java.exe" OSN
Windows 10

Oracle Java 8 version does not turn os.name property into Windows 7 when run in the compatibility mode

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run this code on Windows 10, running in compatibility mode
public class OSN {
  public static void main(String args[]) {
    System.out.println(System.getProperty("os.name"));
  }
}

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Windows 7
ACTUAL -
Windows 10

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class OSN {
  public static void main(String args[]) {
    System.out.println(System.getProperty("os.name"));
  }
}
---------- END SOURCE ----------