fix(compat): add ParserConfig.propertyNamingStrategy for fastjson 1.x compat (#7740)

fastjson 1.x ParserConfig exposes a public propertyNamingStrategy field that
migration code assigns directly, but the compat package lacked it, raising
NoSuchFieldError. Add the field, mirroring SerializeConfig#propertyNamingStrategy
which already exists for the same compatibility reason.

Author: fudianchn

fastjson1-compatible/src/main/java/com/alibaba/fastjson/parser/ParserConfig.java

@@ -1,5 +1,6 @@
 package com.alibaba.fastjson.parser;
 
+import com.alibaba.fastjson.PropertyNamingStrategy;
 import com.alibaba.fastjson.parser.deserializer.ObjectDeserializer;
 import com.alibaba.fastjson2.JSONException;
 import com.alibaba.fastjson2.JSONFactory;
@@ -24,6 +25,13 @@ public static ParserConfig getGlobalInstance() {
 
     final ObjectReaderProvider provider;
     public final boolean fieldBase;
+    /**
+     * Mirrors fastjson 1.x's public field so migration code that assigns it directly
+     * (e.g. {@code parserConfig.propertyNamingStrategy = PropertyNamingStrategy.SnakeCase;})
+     * no longer raises {@link NoSuchFieldError}. Kept for source/binary compatibility,
+     * matching {@link com.alibaba.fastjson.serializer.SerializeConfig#propertyNamingStrategy}.
+     */
+    public PropertyNamingStrategy propertyNamingStrategy;
     private boolean asmEnable;
     private boolean autoTypeSupport;
 

fastjson1-compatible/src/test/java/com/alibaba/fastjson/parser/ParserConfigTest.java

@@ -1,5 +1,6 @@
 package com.alibaba.fastjson.parser;
 
+import com.alibaba.fastjson.PropertyNamingStrategy;
 import com.alibaba.fastjson.parser.deserializer.ObjectDeserializer;
 import com.alibaba.fastjson2.JSONFactory;
 import com.alibaba.fastjson2.JSONObject;
@@ -71,4 +72,16 @@ public void test2() {
 
         assertSame(JSONFactory.getDefaultObjectReaderProvider(), ParserConfig.getGlobalInstance().provider);
     }
+
+    @Test
+    public void propertyNamingStrategyField() {
+        // Regression for issue #7704: fastjson 1.x ParserConfig exposes a public
+        // propertyNamingStrategy field; migration code assigns it directly. The compat
+        // package previously lacked the field, raising NoSuchFieldError. Mirror what
+        // SerializeConfig already exposes.
+        ParserConfig config = new ParserConfig();
+        assertNull(config.propertyNamingStrategy);
+        config.propertyNamingStrategy = PropertyNamingStrategy.SnakeCase;
+        assertSame(PropertyNamingStrategy.SnakeCase, config.propertyNamingStrategy);
+    }
 }