changing the builder method called in ObjectSchemaTest#patternPropertyTranslation() to feed code coverage

Author: erosb

core/src/test/java/org/everit/json/schema/ObjectSchemaTest.java

@@ -258,7 +258,7 @@ public void patternPropertyOnEmptyObjct() {
     @Test
     public void patternPropertyTranslation() {
         ObjectSchema subject = ObjectSchema.builder()
-                .patternProperty("b_.*", BooleanSchema.INSTANCE)
+                .patternProperty(java.util.regex.Pattern.compile("b_.*"), BooleanSchema.INSTANCE)
                 .build();
         Map<java.util.regex.Pattern, Schema> expected = new HashMap<>();
         expected.put(java.util.regex.Pattern.compile("b_.*"), BooleanSchema.INSTANCE);