[fix]Fix BigDecimal precision missing (#347)

diff --git a/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/writer/serializer/JsonDebeziumSchemaSerializer.java b/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/writer/serializer/JsonDebeziumSchemaSerializer.java
index c633264..b980908 100644
--- a/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/writer/serializer/JsonDebeziumSchemaSerializer.java
+++ b/flink-doris-connector/src/main/java/org/apache/doris/flink/sink/writer/serializer/JsonDebeziumSchemaSerializer.java
@@ -20,6 +20,7 @@
 import org.apache.flink.annotation.VisibleForTesting;
 import org.apache.flink.util.StringUtils;
 
+import com.fasterxml.jackson.core.JsonGenerator.Feature;
 import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
@@ -84,9 +85,10 @@
         this.pattern = pattern;
         this.sourceTableName = sourceTableName;
         // Prevent loss of decimal data precision
-        this.objectMapper.enable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS);
         JsonNodeFactory jsonNodeFactory = JsonNodeFactory.withExactBigDecimals(true);
-        this.objectMapper.setNodeFactory(jsonNodeFactory);
+        objectMapper.configure(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS, true);
+        objectMapper.configure(Feature.WRITE_BIGDECIMAL_AS_PLAIN, true);
+        objectMapper.setNodeFactory(jsonNodeFactory);
         this.newSchemaChange = newSchemaChange;
     }