fix consistent with declared orders when alphabetic is false, for issue

#2959

core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java

@@ -180,7 +180,8 @@ public ObjectWriter createObjectWriter(
         }
 
         long writerFieldFeatures = features | beanFeatures;
-        final boolean fieldBased = (writerFieldFeatures & JSONWriter.Feature.FieldBased.mask) != 0 && !objectClass.isInterface();
+        final boolean fieldBased = ((writerFieldFeatures & JSONWriter.Feature.FieldBased.mask) != 0 && !objectClass.isInterface())
+                || !beanInfo.alphabetic;
 
         if (Throwable.class.isAssignableFrom(objectClass)
                 || BeanUtils.isExtendedMap(objectClass)

core/src/test/java/com/alibaba/fastjson2/issues_2900/Issue2959.java

@@ -0,0 +1,40 @@
+package com.alibaba.fastjson2.issues_2900;
+
+import com.alibaba.fastjson2.JSON;
+import com.alibaba.fastjson2.JSONWriter;
+import com.alibaba.fastjson2.annotation.JSONType;
+import lombok.Data;
+import org.junit.jupiter.api.Test;
+
+import java.math.BigDecimal;
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class Issue2959 {
+    @Test
+    public void test() {
+        assertEquals("{\"projectNO\":null,\"orderNO\":null,\"orderType\":null,\"PN\":null,\"qty\":null,\"description\":null,\"customerCode\":null,\"customerName\":null,\"currency\":null,\"netPrice\":null,\"USD\":null,\"rate\":null,\"orderDate\":null,\"requestDate\":null,\"planedDate\":null,\"this$0\":null}",
+                JSON.toJSONString(new TobeDelivery(), JSONWriter.Feature.WriteNulls));
+    }
+
+    @Data
+    @JSONType(alphabetic = false)
+    public class TobeDelivery {
+        private String ProjectNO;
+        private String OrderNO;
+        private String OrderType;
+        private String PN;
+        private Integer Qty;
+        private String Description;
+        private String CustomerCode;
+        private String CustomerName;
+        private String Currency;
+        private BigDecimal NetPrice;
+        private BigDecimal USD;
+        private Float Rate;
+        private Date OrderDate;
+        private Date RequestDate;
+        private Date PlanedDate;
+    }
+}