Logstash encoding issue

Hi,

I am having issue with logstash receiving extra characters when the message is being sent to logstash.

My logstash.conf file looks like -

input {
stdin { codec => plain { charset=>"UTF-8" } }
tcp {
port => 4560
}
}

output {
stdout{}
}

The actual message that is received by logstash from Mulesoft has lot of extra characters -

[2019-11-27T15:44:36,980][WARN ][logstash.codecs.line ][main] Received an event that has a different character encoding than you configured. {:text=>"threadNameq\u0000~\u0000\u0004L\u0000\vthrownProxyt\u00003Lorg/apache/logging/log4j/core/impl/ThrowableProxy;xp\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000'\u0000\u0000\u0000\u0005\u0000\u0000\u0001n\xAD\x89&esr\u00002org.apache.logging.log4j.util.SortedArrayStringMap\xB07ȑs\xEC+\xDC\u0003\u0000\u0002Z\u0000\timmutableI\u0000\tthresholdxp\u0000\u0000\u0000\u0000\u0004w\b\u0000\u0000\u0000\u0004\u0000\u0000\u0000\u0000xsr\u0000>org.apache.logging.log4j.ThreadContext$EmptyThreadContextStack\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0001\u0002\u0000\u0000xpsr\u0000\u001Eorg.apache.logging.log4j.Level\u0000\u0000\u0000\u0000\u0000\u0018 \u001A\u0002\u0000\u0003I\u0000\bintLevelL\u0000\u0004nameq\u0000~\u0000\u0004L\u0000\rstandardLevelt\u0000,Lorg/apache/logging/log4j/spi/StandardLevel;xp\u0000\u0000\u0001\x90t\u0000\u0004INFO~r\u0000org.apache.logging.log4j.spi.StandardLevel\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0012\u0000\u0000xr\u0000\u000Ejava.lang.Enum\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0012\u0000\u0000xpt\u0000\u0004INFOt\u00005org.apache.commons.logging.impl.SLF4JLocationAwareLogt\u00000org.mule.construct.FlowConstructLifecycleManagerpsr\u0000\u0019java.rmi.MarshalledObject|\xBD\u001E\x97\xEDc\xFC>\u0002\u0000\u0003I\u0000\u0004hash[\u0000\blocBytest\u0000\u0002[B[\u0000\bobjBytesq\u0000~\u0000\u0019xp>{\xE1<pur\u0000\u0002[B\xAC\xF3\u0017\xF8\u0006\bT\xE0\u0002\u0000\u0000xp\u0000\u0000\u0000\x90\xAC\xED\u0000\u0005sr\u0000.org.apache.logging.log4j.message.SimpleMessage\x8BtM0`\xB7\xA2\xA8\u0003\u0000\u0001L\u0000\amessaget\u0000\u0012Ljava/lang/String;xpt\u0000Starting flow: get:/getLogstash:api-configxt\u0000*Starting flow: get:/getLogstash:api-configpt\u0000\u000Fqtp595724928-39pxysr\u0000>org.apache.logging.log4j.core.impl.Log4jLogEvent$LogEventProxy\x88-\x9A\u007F\xB2^\xC3\xFD\u0003\u0000\u0010Z\u0000\fisEndOfBatchZ\u0000\u0012isLocationRequiredJ\u0000\bthreadIdI\u0000\u000EthreadPriorityJ\u0000", :expected_charset=>"UTF-8"}

Would appreciate any help on this.

Thanks,
Shiv