title: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation
body: <p>I try to start my spring boot in tomcat server but when I'm adding some external jars to my project :</p>
  
  <pre><code>appsert-rt.jar
  gf-client.jar
  javaee.jar
  </code></pre>
  
  <p>it gives me that error :</p>
  
  <pre><code>  Exception in thread "main" java.lang.IllegalArgumentException: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation (class org.slf4j.impl.JDK14LoggerFactory loaded from file:/C:/Users/amar/Documents/glassfish-3.1/glassfish/modules/bean-validator.jar). If you are using Weblogic you will need to add 'org.slf4j' to prefer-application-packages in WEB-INF/weblogic.xml Object of class [org.slf4j.impl.JDK14LoggerFactory] must be an instance of class ch.qos.logback.classic.LoggerContext
          at org.springframework.util.Assert.isInstanceOf(Assert.java:339)
          at org.springframework.boot.logging.logback.LogbackLoggingSystem.getLoggerContext(LogbackLoggingSystem.java:151)
          at org.springframework.boot.logging.logback.LogbackLoggingSystem.getLogger(LogbackLoggingSystem.java:143)
          at org.springframework.boot.logging.logback.LogbackLoggingSystem.beforeInitialize(LogbackLoggingSystem.java:89)
          at org.springframework.boot.logging.LoggingApplicationListener.onApplicationStartedEvent(LoggingApplicationListener.java:132)
          at org.springframework.boot.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:122)
          at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:151)
          at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:128)
          at org.springframework.boot.context.event.EventPublishingRunListener.publishEvent(EventPublishingRunListener.java:100)
          at org.springframework.boot.context.event.EventPublishingRunListener.started(EventPublishingRunListener.java:54)
          at org.springframework.boot.SpringApplication.run(SpringApplication.java:278)
          at org.springframework.boot.SpringApplication.run(SpringApplication.java:961)
          at org.springframework.boot.SpringApplication.run(SpringApplication.java:950)
          at demo.DemoApplication.main(DemoApplication.java:14)
  </code></pre>
  
  <p>My pom :</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
       &lt;projectxmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchemainstance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0http://maven.apache.org/xsd/maven-4.0.0.xsd"&gt;
  
      &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
  
      &lt;groupId&gt;org.udev&lt;/groupId&gt;
      &lt;artifactId&gt;udev&lt;/artifactId&gt;
      &lt;version&gt;0.0.1-SNAPSHOT&lt;/version&gt;
      &lt;packaging&gt;war&lt;/packaging&gt;
  
      &lt;name&gt;demo&lt;/name&gt;
      &lt;description&gt;Demo project for Spring Boot&lt;/description&gt;
  
      &lt;parent&gt;
          &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
          &lt;artifactId&gt;spring-boot-starter-parent&lt;/artifactId&gt;
          &lt;version&gt;1.2.1.RELEASE&lt;/version&gt;
          &lt;relativePath/&gt; &lt;!-- lookup parent from repository --&gt;
      &lt;/parent&gt;
  
      &lt;properties&gt;
          &lt;project.build.sourceEncoding&gt;UTF-8&lt;/project.build.sourceEncoding&gt;
          &lt;start-class&gt;demo.DemoApplication&lt;/start-class&gt;
          &lt;java.version&gt;1.8&lt;/java.version&gt;
      &lt;/properties&gt;
  
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-web&lt;/artifactId&gt;
          &lt;/dependency&gt;
  
              &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-security&lt;/artifactId&gt;
          &lt;/dependency&gt;
  
          &lt;dependency&gt;
  
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-tomcat&lt;/artifactId&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.apache.tomcat.embed&lt;/groupId&gt;
              &lt;artifactId&gt;tomcat-embed-jasper&lt;/artifactId&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-test&lt;/artifactId&gt;
              &lt;scope&gt;test&lt;/scope&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.data&lt;/groupId&gt;
              &lt;artifactId&gt;spring-data-jpa&lt;/artifactId&gt;
              &lt;version&gt;1.6.4.RELEASE&lt;/version&gt;
              &lt;type&gt;jar&lt;/type&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;javax.servlet&lt;/groupId&gt;
              &lt;artifactId&gt;jstl&lt;/artifactId&gt;
          &lt;/dependency&gt;
           &lt;dependency&gt;
              &lt;groupId&gt;org.projectlombok&lt;/groupId&gt;
              &lt;artifactId&gt;lombok&lt;/artifactId&gt;
              &lt;version&gt;1.14.8&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
            &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
              &lt;artifactId&gt;spring-boot-starter-data-jpa&lt;/artifactId&gt;
          &lt;/dependency&gt;
            &lt;dependency&gt;
              &lt;groupId&gt;mysql&lt;/groupId&gt;
              &lt;artifactId&gt;mysql-connector-java&lt;/artifactId&gt;
            &lt;/dependency&gt;
  
  
      &lt;/dependencies&gt;
  
      &lt;build&gt;
          &lt;plugins&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
                  &lt;artifactId&gt;spring-boot-maven-plugin&lt;/artifactId&gt;
              &lt;/plugin&gt;
          &lt;/plugins&gt;
      &lt;/build&gt;
  
    &lt;/project&gt;
  </code></pre>
  
  <p>note : it work perfectly when i remove the jars / One problem could be conflits between classes of slf4j in my maven added jars and those added externelly</p>