ThreadContext in append() method of an Appender plugin?

package com.foo.bar;

import java.io.Serializable;
import org.apache.logging.log4j.ThreadContext;
import org.apache.logging.log4j.core.AbstractLifeCycle;
import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.Core;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.appender.SocketAppender;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderFactory;
import org.apache.logging.log4j.core.net.AbstractSocketManager;
import org.apache.logging.log4j.core.net.Advertiser;
import org.apache.logging.log4j.core.net.Protocol;

import com.ibm.commerce.ras.DDThreadContextManager;
import com.ibm.websphere.management.AdminService;
import com.ibm.websphere.management.AdminServiceFactory;

/**
 * Overrides SocketAppender so that thread-local information can be
 * stored for a LoggingEvent before it is sent over the wire.
 * 
 */
@Plugin(
          name = "MySocketAppender", 
          category = Core.CATEGORY_NAME,
          elementType = Appender.ELEMENT_TYPE,
          printObject = true)
public class MySocketAppender extends SocketAppender {
    
    protected MySocketAppender(String name, Layout<? extends Serializable> layout, Filter filter, AbstractSocketManager manager, boolean ignoreExceptions, boolean immediateFlush, Advertiser advertiser, Property[] properties) {
        super(name, layout, filter, manager, ignoreExceptions, immediateFlush, advertiser, properties);
    }
    
    @PluginBuilderFactory
    public static Builder newBuilder() {
        return new Builder();
    }
    
    @Override
    public void append(LogEvent event) {
        ThreadContext.put("Thread ID", Thread.currentThread().getName() + DDThreadContextManager.getThreadTraceId());
        ThreadContext.put("Client ID", DDThreadContextManager.getThreadSessionId());

        AdminService adminService = AdminServiceFactory.getAdminService();
        String processName = (adminService != null) ? adminService.getProcessName() : "null";
        ThreadContext.put("App server", processName == null ? "null" : processName);
        
        super.append(event);
        
        ThreadContext.clearAll();
    }
    
    /**
     * Builds a MySocketAppender.
     */
    public static class Builder extends SocketAppender.Builder {        
        @Override
        public MySocketAppender build() {
            boolean immediateFlush = isImmediateFlush();
            final boolean bufferedIo = isBufferedIo();
            final Layout<? extends Serializable> layout = getLayout();
            if (layout == null) {
                AbstractLifeCycle.LOGGER.error("No layout provided for MySocketAppender");
                return null;
            }            

            final String name = getName();
            if (name == null) {
                AbstractLifeCycle.LOGGER.error("No name provided for MySocketAppender");
                return null;
            }

            final Protocol protocol = getProtocol();
            final Protocol actualProtocol = protocol != null ? protocol : Protocol.TCP;
            if (actualProtocol == Protocol.UDP) {
                immediateFlush = true;
            }

            final AbstractSocketManager manager = SocketAppender.createSocketManager(name, actualProtocol, getHost(), getPort(),
                    getConnectTimeoutMillis(), getSslConfiguration(), getReconnectDelayMillis(), getImmediateFail(), layout, getBufferSize(), getSocketOptions());

            return new MySocketAppender(name, layout, getFilter(), manager, isIgnoreExceptions(),
                    !bufferedIo || immediateFlush, getAdvertise() ? getConfiguration().getAdvertiser() : null,
                    getPropertyArray());
        }
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="debug" packages="com.foo.bar">
    <Properties>
        <Property name="baseDir">C:/temp</Property>
    </Properties>
    
    <Appenders>
        <MySocketAppender name="socket" host="localhost" port="11005" reconnectionDelayMillis="1000" >
            <JsonLayout properties="true" compact="true" />
        </MySocketAppender>
     
        <MyConsoleAppender name="console">
            <PatternLayout pattern="%-5p %d{ISO8601} - %n%m%nThread ID: &lt;%X{Thread ID}&gt;%nClient ID: &lt;%X{Client ID}&gt;%nApp Server: &lt;%X{App server}&gt;%n%n" />
        </MyConsoleAppender>
    </Appenders>
    
    <Loggers>
        <Root level="DEBUG">
             <Appender-Ref ref="socket" />
        </Root>
    </Loggers>
</Configuration>