NIFI-14496 Support converting Object array of bytes to String for Records

This closes apache#9901

Signed-off-by: David Handermann <exceptionfactory@apache.org>

Author: pvillard31

nifi-commons/nifi-record/src/main/java/org/apache/nifi/serialization/record/field/ObjectStringFieldConverter.java

@@ -96,6 +96,18 @@ public String convertField(final Object field, final Optional<String> pattern, f
                     throw new FieldConversionException(String.class, field, name, e);
                 }
             }
+            case Object[] objectArray -> {
+                if (objectArray.length > 0) {
+                    final byte[] converted = new byte[objectArray.length];
+                    for (int i = 0; i < objectArray.length; i++) {
+                        converted[i] = (byte) objectArray[i];
+                    }
+                    return new String(converted, StandardCharsets.UTF_8);
+                } else {
+                    // Handle an empty array as an empty string
+                    return "";
+                }
+            }
             default -> {
             }
         }

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

@@ -19,6 +19,7 @@
 import org.apache.nifi.serialization.record.RecordFieldType;
 import org.junit.jupiter.api.Test;
 
+import java.nio.charset.StandardCharsets;
 import java.sql.Timestamp;
 import java.time.LocalDateTime;
 import java.time.ZoneId;
@@ -45,6 +46,8 @@ class ObjectStringFieldConverterTest {
 
     private static final String DATE_TIME_ZONE_OFFSET_PATTERN = "yyyy-MM-dd HH:mm:ssZZZZZ";
 
+    private static final String EMPTY_STRING = "";
+
     @Test
     void testConvertFieldNull() {
         final String string = CONVERTER.convertField(null, Optional.of(DEFAULT_PATTERN), FIELD_NAME);
@@ -120,6 +123,28 @@ void testConvertFieldDateZoneOffsetPattern() {
         assertEquals(dateTimeZoneOffsetExpected, string);
     }
 
+    @Test
+    void testConvertFieldObjectArray() {
+        final String expected = String.class.getSimpleName();
+        final byte[] bytes = expected.getBytes(StandardCharsets.UTF_8);
+
+        final Object[] objectArray = new Object[bytes.length];
+        for (int i = 0; i < bytes.length; i++) {
+            objectArray[i] = bytes[i];
+        }
+
+        final String string = CONVERTER.convertField(objectArray, Optional.empty(), FIELD_NAME);
+        assertEquals(expected, string);
+    }
+
+    @Test
+    void testConvertFieldObjectArrayEmpty() {
+        final Object[] objectArray = new Object[0];
+
+        final String string = CONVERTER.convertField(objectArray, Optional.empty(), FIELD_NAME);
+        assertEquals(EMPTY_STRING, string);
+    }
+
     private String getDateTimeZoneOffset() {
         final Timestamp inputTimestamp = Timestamp.valueOf(DATE_TIME_DEFAULT);
         final LocalDateTime inputLocalDateTime = inputTimestamp.toLocalDateTime();