ITS Filter: a test failure in ParametersTest.customValuesNotWrittenAsString on Windows

The test was introduced in the scope of issue #1427.

Below is the error description:

[INFO] Running net.sf.okapi.filters.its.ParametersTest
[ERROR] Tests run: 3, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.047 s <<< FAILURE! -- in net.sf.okapi.filters.its.ParametersTest
[ERROR] net.sf.okapi.filters.its.ParametersTest.customValuesNotWrittenAsString -- Time elapsed: 0.047 s <<< FAILURE!
org.junit.ComparisonFailure:
expected:<...link" version="1.0">[
<!-- See ITS specification at: http://www.w3.org/TR/its/ -->]
</its:rules>> but was:<...link" version="1.0">[
]!-- See ITS specification at: http://www.w3.org/TR/its/ -->
</its:rules>>
        at org.junit.Assert.assertEquals(Assert.java:117)
        at org.junit.Assert.assertEquals(Assert.java:146)
        at net.sf.okapi.filters.its.ParametersTest.customValuesNotWrittenAsString(ParametersTest.java:39)