NIFI-5664 Support ArrayList in DataTypeUtils#toArray

NIFI-5664 Generalize to handling List

This closes apache#3049

Signed-off-by: Mike Thomsen <mikerthomsen@gmail.com>

nifi-commons/nifi-record/src/main/java/org/apache/nifi/serialization/record/util/DataTypeUtils.java

@@ -339,6 +339,11 @@ public static Object[] toArray(final Object value, final String fieldName, final
             return dest;
         }
 
+        if (value instanceof List) {
+            final List<?> list = (List<?>)value;
+            return list.toArray();
+        }
+
         throw new IllegalTypeConversionException("Cannot convert value [" + value + "] of type " + value.getClass() + " to Object Array for field " + fieldName);
     }
 

nifi-commons/nifi-record/src/test/java/org/apache/nifi/serialization/record/TestDataTypeUtils.java

@@ -24,6 +24,7 @@
 import java.nio.charset.StandardCharsets;
 import java.sql.Timestamp;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -168,6 +169,18 @@ public void testConvertRecordFieldToObject() {
 
     }
 
+    @Test
+    public void testToArray() {
+        final List<String> list = Arrays.asList("Seven", "Eleven", "Thirteen");
+
+        final Object[] array = DataTypeUtils.toArray(list, "list", null);
+
+        assertEquals(list.size(), array.length);
+        for (int i = 0; i < list.size(); i++) {
+            assertEquals(list.get(i), array[i]);
+        }
+    }
+
     @Test
     public void testStringToBytes() {
         Object bytes = DataTypeUtils.convertType("Hello", RecordFieldType.ARRAY.getArrayDataType(RecordFieldType.BYTE.getDataType()),null, StandardCharsets.UTF_8);