Add null-conditional operators on these 3 files (#6007)

* add null conditional operators on these 3 files . To aviod some agent exception of Oracle jdbc.

* Add a line in Java Agent section of CHANGES.md file
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

CHANGES.md

@@ -13,6 +13,7 @@ Release Notes.
 * Fix jdk-http and okhttp-3.x plugin did not overwrite the old trace header.
 * Support collecting logs of log4j, log4j2, and logback in the tracing context with a new `logger-plugin`.
 * Fix the unexpected RunningContext recreation in the Tomcat plugin.
+* Fix the potential NPE when trace_sql_parameters is enabled.
 
 #### OAP-Backend
 * Make meter receiver support MAL.

apm-sniffer/apm-sdk-plugin/jdbc-commons/src/main/java/org/apache/skywalking/apm/plugin/jdbc/JDBCPreparedStatementIgnorableSetterInterceptor.java

@@ -31,8 +31,10 @@ public class JDBCPreparedStatementIgnorableSetterInterceptor implements Instance
     public final void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
         Class<?>[] argumentsTypes, MethodInterceptResult result) throws Throwable {
         final StatementEnhanceInfos statementEnhanceInfos = (StatementEnhanceInfos) objInst.getSkyWalkingDynamicField();
-        final int index = (Integer) allArguments[0];
-        statementEnhanceInfos.setParameter(index, Constants.SQL_PARAMETER_PLACEHOLDER);
+        if (statementEnhanceInfos != null) {
+          final int index = (Integer) allArguments[0];
+          statementEnhanceInfos.setParameter(index, Constants.SQL_PARAMETER_PLACEHOLDER);
+        }
     }
 
     @Override

apm-sniffer/apm-sdk-plugin/jdbc-commons/src/main/java/org/apache/skywalking/apm/plugin/jdbc/JDBCPreparedStatementNullSetterInterceptor.java

@@ -30,8 +30,10 @@ public class JDBCPreparedStatementNullSetterInterceptor implements InstanceMetho
     public final void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
         Class<?>[] argumentsTypes, MethodInterceptResult result) throws Throwable {
         final StatementEnhanceInfos statementEnhanceInfos = (StatementEnhanceInfos) objInst.getSkyWalkingDynamicField();
-        final int index = (Integer) allArguments[0];
-        statementEnhanceInfos.setParameter(index, "NULL");
+        if (statementEnhanceInfos != null) {
+          final int index = (Integer) allArguments[0];
+          statementEnhanceInfos.setParameter(index, "NULL");
+        }
     }
 
     @Override

apm-sniffer/apm-sdk-plugin/jdbc-commons/src/main/java/org/apache/skywalking/apm/plugin/jdbc/JDBCPreparedStatementSetterInterceptor.java

@@ -30,9 +30,11 @@ public class JDBCPreparedStatementSetterInterceptor implements InstanceMethodsAr
     public final void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
         Class<?>[] argumentsTypes, MethodInterceptResult result) throws Throwable {
         final StatementEnhanceInfos statementEnhanceInfos = (StatementEnhanceInfos) objInst.getSkyWalkingDynamicField();
-        final int index = (Integer) allArguments[0];
-        final Object parameter = allArguments[1];
-        statementEnhanceInfos.setParameter(index, parameter);
+        if (statementEnhanceInfos != null) {
+          final int index = (Integer) allArguments[0];
+          final Object parameter = allArguments[1];
+          statementEnhanceInfos.setParameter(index, parameter);
+        }
     }
 
     @Override