Maven Resources Plugin copy error when filtering is true on a Mac

This is an error consistently seen on Mac (OS X 10.11.6), but it seems to work fine on linux (our jenkins agent).

Basically, when `filtering` is set to true in the resources plugin, the resource file contents are copied incorrectly converting \${something} to ${something}. Note the missing back-slash, and also that "something" is not a maven variable. The expected behavior is to keep it unchanged. Here is a unit test that shows the issue:
1. First, create a resource text file "new.test" with just the string

\${something }

2. Make sure that resource plugin has filtering set to "true":

<testResources>
      <testResource>
        <directory>src/test/resources</directory>
        <filtering>true</filtering>
      </testResource>

3. Create the unit test below:

@Test
public void test() throws IOException {
    URL url = Resources.getResource("conf/new.test");
    String text = Resources.toString(url, Charsets.UTF_8);
    String expectedText = "\\${something }" ;
    System.out.println("actual: " + text);
    System.out.println("expected: " + expectedText);

    assertEquals(expectedText, text);
}

3. Note that when you run the above test from the IDE directly, it passes.
4. Run `mvn clean install` from command line and verify the following error:

actual: ${something }
expected: \${something }

org.junit.ComparisonFailure: 
Expected :\${something }
Actual   :${something }  ---> Note the back-slash has gone missing.