dependsOnGroups annotation in Test NG

@Test(groups = { "init" }) public correctVM() {}

@Test(groups = { "init" }) public serverStartedOk() {}

@Test(dependsOnGroups = { "init.* }) public method1() {}

// Above TestNG code

in method1, for the dependsOnGroups regular expression is used. Is it mandatory to use regEx or is it okay to give "init" as all groups are having name as init.