SLF4J API is a simple API that allows to plug in any desired logging library at deployment time.

Here is the source code for SLF4J API 1.7.31. You can download its pre-compiled version slf4j-api-1.7.31.jar at SLF4J Download Website.

⏎ org/slf4j/helpers/NOPMDCAdapter.java

/**
 * Copyright (c) 2004-2011 QOS.ch
 * All rights reserved.
 *
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 *
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 *
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package org.slf4j.helpers;

import java.util.Map;

import org.slf4j.spi.MDCAdapter;

/**
 * This adapter is an empty implementation of the {@link MDCAdapter} interface.
 * It is used for all logging systems which do not support mapped
 * diagnostic contexts such as JDK14, simple and NOP. 
 * 
 * @author Ceki Gülcü
 * 
 * @since 1.4.1
 */
public class NOPMDCAdapter implements MDCAdapter {

    public void clear() {
    }

    public String get(String key) {
        return null;
    }

    public void put(String key, String val) {
    }

    public void remove(String key) {
    }

    public Map<String, String> getCopyOfContextMap() {
        return null;
    }

    public void setContextMap(Map<String, String> contextMap) {
        // NOP
    }

}

⏎ org/slf4j/helpers/NOPMDCAdapter.java

Or download all of them as a single archive file:

File name: slf4j-api-1.7.31-sources.jar
File size: 58728 bytes
Release date: 2021-06-17
Download 

⇒ Source Code for SLF4J 1.7.31 Simple Logging

⇐ Source Code for SLF4J Migrator

⇑ Downloading and Reviewing SLF4J Packages

⇑⇑ SLF4J - Simple Logging Facade for Java