Adding regression test against malicious input (#12105)

server/src/test/java/com/vaadin/data/validator/EmailValidatorTest.java

                 validator("one-letter tld not allowed"));
     }
 
+    @Test
+    public void testEmailValidatorWithBadInput() {
+        assertFails("a@a.m5qRt8zLxQG4mMeu9yKZm5qRt8zLxQG4mMeu9yKZm5qRt8zLxQG4mMeu9yKZ&",validator("validator not halting on bad input"));
+    }
+
     @Test
     public void testLongTldPasses() {
         assertPasses("joonas@vaadin.management", shouldNotFail());