Special Character Issue : MQ message PUT error : java.nio.charset.UnmappableCharacterException

I have a setup where there is a JMS Producer and JMS receiver. The sender application sends a message like :

source text ⟨е, ё, и, ю, я⟩  abcdefg

JMS receiver after receiving the message, puts it to a IBM MQ queue using pure IBM MQ API classes.

While putting this message to MQ I am getting the below exception:

INFO  | 2020-09-17 09:45:19 | [main] mimq.MQReceiver (MQReceiver.java:211) - IO Exception Occurred: Input length = 1
java.nio.charset.UnmappableCharacterException: Input length = 1
        at java.nio.charset.CoderResult.throwException(CoderResult.java:282)
        at java.nio.charset.CharsetEncoder.encode(CharsetEncoder.java:816)
        at com.ibm.mq.jmqi.system.JmqiCodepage.stringToBytes(JmqiCodepage.java:923)
        at com.ibm.mq.MQMessage.writeString(MQMessage.java:2848)
        at com.ibm.mimq.MQReceiver.sendToAnotherQueue(MQReceiver.java:192)
        at com.ibm.mimq.MQReceiver.main(MQReceiver.java:113)

Below is my MQ PUT code :

public static void sendToLocalQueue(String msg) {
    
    int port = 1414;
    String host = "some-host";
    String channel = "some-channel";
    String manager = "some-QM";
    String user = "user"; 
    String passwd = "passwd";
    String qname = "TEST";
    String qmname = "some-QM";
    
    MQQueueManager qMgr;
    MQQueue inputQ;
    
    try {       
        
        Hashtable<String, String> h = new Hashtable<String, String>();
        h.put(MQC.TRANSPORT_PROPERTY, MQC.TRANSPORT_MQSERIES_CLIENT);
        MQEnvironment.properties = h;
        MQEnvironment.hostname  = host;
        MQEnvironment.port      = port;
        MQEnvironment.channel   = channel;
        
        MQEnvironment.userID    = user;
        MQEnvironment.password  = passwd;
        MQEnvironment.disableTracing();
        MQException.log = null;
        qMgr = new MQQueueManager(manager);
        
        MQMessage m = new MQMessage();      
        m.applicationOriginData = "AMPS";
        m.messageType   = MQC.MQMT_DATAGRAM;
        m.format        = MQC.MQFMT_STRING;
        m.encoding      = MQC.MQENC_NATIVE;
        m.priority      = 4;
        m.persistence   = MQC.MQPER_PERSISTENT;
        m.characterSet  = MQC.MQCCSI_Q_MGR;
        //m.characterSet = 1208;
        m.expiry        =  MQC.MQEI_UNLIMITED;
        m.writeString(msg);
        
        MQPutMessageOptions putOptions = new MQPutMessageOptions();
        putOptions.options = MQC.MQPMO_SYNCPOINT | MQC.MQPMO_FAIL_IF_QUIESCING; 
        
        logger.info("Putting message to LAN MQ (TEST queue)....");          
        qMgr.put(qname, qmname, m, putOptions);
        qMgr.commit();
        
        
    } catch(MQException me) {
        logger.info("Error Code       : "  +me.getErrorCode());
        logger.info("LocalizedMessage : "  +me.getLocalizedMessage());
        logger.info("Message          : "  +me.getMessage());
        logger.info("Reason           : "  +me.getReason());
        me.printStackTrace();
        
    } catch (IOException e) {
        // TODO Auto-generated catch block
        logger.info("IO Exception Occurred       : "  +e.getLocalizedMessage());
        e.printStackTrace();
    }       
}

It is unable to put the message to the queue due to Unmappable character. The encoding is set to UTF-8 at Queue Manager level.

However when I replace the below line : m.characterSet = MQC.MQCCSI_Q_MGR;

With the line : m.characterSet = 1208; The issue is no more there.

My question is why this conversion is not getting done at MQ level. What are settings I need to check to ensure the correct conversion. I have tried the below techniques, but not working :

Setting java parameter as : -Dfile.encoding=UTF-8 

My environment :

Server : Linux
MQ : 9.0  or 7.5
Java : 1.8

One more thing to mention, the same setup was working with 7.5 but not working with MQ 9.0 after migration. I know with my above one line code change I can pass the message. But I want to understand in MQ level, if I am missing out some configurations. Any advise would be much appreciated.

Thank You.

UPDATE

The Client Machine from where I am sending the Message over to MQ has CCSID : MQMD.CodedCharSetId = 1208

The MQ server where I am connecting and sending the message has this :

getDefaultProperty(Object) returns [819(0x333)] Integer
setCCSID(int) setter [819(0x333)]

So when I am setting 1208 explicitely in my code it is working. When not the conversion is failing.

UPDATE-2

The value MQC.MQCCSI_Q_MGR is Zero as I saw in the jar. Hence the code is designed like this, if the value is Zero, it will fetch the default value from the Jar which is set to 819. I learnt this when I turned on the MQ tracing. And the code is like this :

getDefaultProperty(Object) returns [819(0x333)] Integer
setCCSID(int) setter [819(0x333)]

This code is present inside the jar. So we need to explicitly set the charset value on the message. In my case it is 1208.