Unable to create temporary file using createTempFile method if System.getProperty("file.separator") is used

FULL PRODUCT VERSION :
java version "1.8.0_74"
Java(TM) SE Runtime Environment (build 1.8.0_74-b02)
Java HotSpot(TM) Client VM (build 25.74-b02, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Win7 - 64 bit

A DESCRIPTION OF THE PROBLEM :
I'am trying to create a temp directory using the following code
public static File createTemporaryDirectory() {
        File file = null;
        try {
            file =
                File.createTempFile("xyz", "Directory" + System.getProperty("file.separator"));
            file.delete();
            file.mkdirs();
        } catch (final IOException e) {
            e.printStackTrace();
        }
        return file;
    }
We want our product to be compatible with both 1.6 and 1.8 , but the above code doesnt work in 1.8 . I did some research and found that if i remove System.getProperty("file.separator") it works fine .

Since i cant debug the java library code , i want to know is there any change in the code of createTempFile ; i.e. in 1.6 it didnt took care of file separator but in 1.8 it does and that is the reason why i get the following exception

java.io.IOException: Unable to create temporary file, C:\Users\xxx\AppData\Local\Temp\xyz3408962131679677845Directory.

I know in 1.8 there is a new method introduced to createTempDirectory to create temp directory , but we want our product to be compatible with both 1.6 and 1.8 .


REGRESSION. Last worked in version 6u45

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_74"
Java(TM) SE Runtime Environment (build 1.8.0_74-b02)
Java HotSpot(TM) Client VM (build 25.74-b02, mixed mode, sharing)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Following code throws an exception
public static File createTemporaryDirectory() {
        File file = null;
        try {
            file =
                File.createTempFile("xyz", "Directory" + System.getProperty("file.separator"));
        } catch (final IOException e) {
            e.printStackTrace();
        }
        return file;
    }

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
a new file object
ACTUAL -
java.io.IOException: Unable to create temporary file, C:\Users\xxxAppData\Local\Temp\xyz3408962131679677845Directory

ERROR MESSAGES/STACK TRACES THAT OCCUR :
java.io.IOException: Unable to create temporary file, C:\Users\xxx\AppData\Local\Temp\xyz3408962131679677845Directory
at java.io.File$TempDirectory.generateFile(File.java:1921)
at java.io.File.createTempFile(File.java:2010)
at java.io.File.createTempFile(File.java:2070)

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Remove System.getProperty("file.separator") from createTempFIle