fix null pointer exception for hasValue in a repeating group when there is no value

Author: RyanHealey

src/main/java/com/lmax/simpledsl/internal/RepeatingParamValues.java

@@ -22,7 +22,8 @@ class RepeatingParamValues implements RepeatingGroup
     @Override
     public boolean hasValue(final String name)
     {
-        return !getValues(name).isEmpty();
+        final List<String> values = getValues(name);
+        return !(values == null || values.isEmpty());
 
     }
 

src/test/java/com/lmax/simpledsl/internal/RepeatingParamValuesTest.java

@@ -27,7 +27,6 @@
 import java.util.Map;
 
 import static java.util.Arrays.asList;
-import static java.util.Collections.emptyList;
 import static org.junit.jupiter.api.Assertions.assertArrayEquals;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
@@ -84,7 +83,6 @@ public void shouldNotReportOptionalValueAsPresentWhenNoValueProvided()
         final OptionalArg otherArg = new OptionalArg("bar");
         final Map<String, List<String>> values = new HashMap<>();
         values.put("foo", Collections.singletonList("abc"));
-        values.put("bar", emptyList());
         final RepeatingParamValues params = new RepeatingParamValues(asList(requiredArg, otherArg).toArray(new DslArg[0]), values);
 
         assertFalse(params.hasValue("bar"));