FieldMap - enhancing thrown exception for null values (#567)

* 458 Core - FieldMap - enhancing thrown exception for null values

* 458 Core - FieldMap - replacing SessionRejectReasonText

* 458 Core - MessageTest - Fixing testMessageSetGetString failure

Author: vinipx

quickfixj-core/src/main/java/quickfix/FieldMap.java

@@ -337,7 +337,7 @@ public void setField(int key, Field<?> field) {
 
     public void setField(StringField field) {
         if (field.getValue() == null) {
-            throw new NullPointerException("Null field values are not allowed.");
+            throw new FieldException(SessionRejectReason.TAG_SPECIFIED_WITHOUT_A_VALUE, field.getField());
         }
         fields.put(field.getField(), field);
     }

quickfixj-core/src/test/java/quickfix/FieldMapTest.java

@@ -1,20 +1,21 @@
 package quickfix;
 
-import java.math.BigDecimal;
-import java.time.LocalDateTime;
-import java.time.LocalTime;
-import java.time.ZoneOffset;
+import org.junit.Test;
 import quickfix.field.EffectiveTime;
 import quickfix.field.MDEntryTime;
 import quickfix.field.converter.UtcTimeOnlyConverter;
 
+import java.math.BigDecimal;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.ZoneOffset;
 import java.util.Iterator;
 import java.util.Optional;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
-import org.junit.Test;
 
 /**
  * Tests the {@link FieldMap} class.
@@ -79,16 +80,16 @@ private void testOrdering(int[] vals, int[] order, int[] expected) {
 
     @Test
     public void testOrdering() {
-        testOrdering(new int[] { 1, 2, 3 }, null, new int[] { 1, 2, 3 });
-        testOrdering(new int[] { 3, 2, 1 }, null, new int[] { 1, 2, 3 });
-        testOrdering(new int[] { 1, 2, 3 }, new int[] { 1, 2, 3 }, new int[] { 1, 2, 3 });
-        testOrdering(new int[] { 3, 2, 1 }, new int[] { 1, 2, 3 }, new int[] { 1, 2, 3 });
-        testOrdering(new int[] { 1, 2, 3 }, new int[] { 1, 3, 2 }, new int[] { 1, 3, 2 });
-        testOrdering(new int[] { 3, 2, 1 }, new int[] { 1, 3, 2 }, new int[] { 1, 3, 2 });
-        testOrdering(new int[] { 1, 2, 3 }, new int[] { 1, 3 }, new int[] { 1, 3, 2 });
-        testOrdering(new int[] { 3, 2, 1 }, new int[] { 1, 3 }, new int[] { 1, 3, 2 });
-        testOrdering(new int[] { 1, 2, 3 }, new int[] { 3, 1 }, new int[] { 3, 1, 2 });
-        testOrdering(new int[] { 3, 2, 1 }, new int[] { 3, 1 }, new int[] { 3, 1, 2 });
+        testOrdering(new int[]{1, 2, 3}, null, new int[]{1, 2, 3});
+        testOrdering(new int[]{3, 2, 1}, null, new int[]{1, 2, 3});
+        testOrdering(new int[]{1, 2, 3}, new int[]{1, 2, 3}, new int[]{1, 2, 3});
+        testOrdering(new int[]{3, 2, 1}, new int[]{1, 2, 3}, new int[]{1, 2, 3});
+        testOrdering(new int[]{1, 2, 3}, new int[]{1, 3, 2}, new int[]{1, 3, 2});
+        testOrdering(new int[]{3, 2, 1}, new int[]{1, 3, 2}, new int[]{1, 3, 2});
+        testOrdering(new int[]{1, 2, 3}, new int[]{1, 3}, new int[]{1, 3, 2});
+        testOrdering(new int[]{3, 2, 1}, new int[]{1, 3}, new int[]{1, 3, 2});
+        testOrdering(new int[]{1, 2, 3}, new int[]{3, 1}, new int[]{3, 1, 2});
+        testOrdering(new int[]{3, 2, 1}, new int[]{3, 1}, new int[]{3, 1, 2});
     }
 
     @Test
@@ -111,14 +112,21 @@ public void testOptionalDecimal() {
         assertFalse(map.getOptionalDecimal(6).isPresent());
     }
 
+    @Test
+    public void testNullFieldException() {
+        FieldMap map = new Message();
+        StringField field = new StringField(0, null);
+        assertThrows(FieldException.class, () -> map.setField(field));
+    }
+
     private long epochMilliOfLocalDate(LocalDateTime localDateTime) {
         return localDateTime.toInstant(ZoneOffset.UTC).toEpochMilli();
     }
 
     @Test
     public void testRemoveGroup() {
         FieldMap map = new Message();
-        Group group = new Group(73,11);
+        Group group = new Group(73, 11);
         map.addGroup(group);
         assertTrue(map.hasGroup(73));
         map.removeGroup(73);