title: Slf4j with log4j2 not working Spring boot 1.4.3.RELEASE
body: <p>I was using Spring boot 1.3.6.RELEASE and <code>log4j2.yml</code> as below:</p>
  
  <pre><code>Configuration:
    status: info
  
    Properties:
      Property:
        name: log-path
        value: "/dvl-log/pol/apps/logs/api"
  
    Appenders:
      Console:
        - name: Console
          target: SYSTEM_OUT
          PatternLayout:
            Pattern: "%d{HH:mm:ss.SSS} %-5level %logger{1} - %msg%n"
  
    Loggers:
      Root:
        level: info
        AppenderRef:
          - ref: Console
      Logger:
      - name: com.company.api
        level: trace
        additivity: false
        AppenderRef:
          - ref: Console
            level: trace
  </code></pre>
  
  <p>The logging with below code was working perfectly.</p>
  
  <pre><code>@Slf4j
  public class LogExample{
        public void logMethods(String className,String methodName){
  
          log.trace("{} &gt;&gt; {}", className, methodName);
        }
  }
  </code></pre>
  
  <p>But when I upgraded to Spring Boot 1.4.3.RELEASE, the logger is not working.</p>
  
  <p>My new build.gradle after upgrading to 1.4.3 is (just a version change)</p>
  
  <pre><code>version '1.0'
  // dependencies for command line
  buildscript {
      ext {
          springBootVersion = '1.4.3.RELEASE'
          dependencyManagementVersion = '0.5.2.RELEASE'
      }
      repositories {
          jcenter()
      }
      dependencies {
          classpath "org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}"
          classpath "io.spring.gradle:dependency-management-plugin:${dependencyManagementVersion}"
      }
  }
  
  apply plugin: "io.spring.dependency-management"
  apply plugin: 'java'
  apply plugin: 'spring-boot'
  apply plugin: 'war'
  apply plugin: 'eclipse'
  apply plugin: 'idea'
  
  // JDK 8
  sourceCompatibility = JavaVersion.VERSION_1_8
  targetCompatibility = JavaVersion.VERSION_1_8
  
  repositories {
      jcenter()
  }
  
  ext {
      springCloudVersion = 'Brixton.SR4'
      springBootVersion = '1.4.3.RELEASE'
      swaggerVersion = '2.4.0'
      jodaTimeVersion = '2.9.4'
      jacksonJodaVersion = '2.5.1'
      junitVersion = '4.12'
      springWsTestVersion = '2.2.3.RELEASE'
      lombokVersion = '1.16.10'
      jsonPathVersion = '2.2.0'
      ehcacheVersion = '3.2.0'
      javaxCacheVersion = '1.0.0'
  }
  
  dependencyManagement {
      imports {
          mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
          mavenBom "org.springframework.boot:spring-boot-starter-parent:${springBootVersion}"
      }
  }
  
  sourceSets {
      test {
          java {
              srcDir 'src/test/unit/java'
          }
          resources {
              srcDir 'src/test/unit/resources'
          }
      }
  }
  
  dependencies {
  
      /* core libraries */
      compile('org.springframework.cloud:spring-cloud-starter-config') {
          exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
      }
      compile('org.springframework.boot:spring-boot-starter-web') {
          exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
      }
      compile("org.springframework.boot:spring-boot-starter-hateoas"){
          exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
      }
      compile 'org.springframework.ws:spring-ws-core'
  
      // logging
      compile('org.springframework.boot:spring-boot-starter-log4j2')
      compile('com.fasterxml.jackson.dataformat:jackson-dataformat-yaml')
      compile('com.fasterxml.jackson.core:jackson-databind')
  
      // embedded server
      providedRuntime('org.springframework.boot:spring-boot-starter-tomcat')
  
  
      // https://mvnrepository.com/artifact/org.projectlombok/lombok-maven
      compile "org.projectlombok:lombok:${lombokVersion}"
  
      // https://mvnrepository.com/artifact/com.jayway.jsonpath/json-path
      // A Java DSL for reading JSON documents
      compile "com.jayway.jsonpath:json-path:${jsonPathVersion}"
  
  
      /* plugins */
  
      /* test libraries */
      // unit
      testCompile "junit:junit:${junitVersion}"
      testCompile "org.springframework.boot:spring-boot-starter-test"
      testCompile "org.springframework.ws:spring-ws-test:${springWsTestVersion}"
  }
  
  war {
      archiveName = "${project.name}.war"
  }
  </code></pre>
  
  <p>What thing I'm missing here? TIA</p>
  
  <p>I want to add <strong>more details</strong>:
  there are log4j-api:2.6.2, log4j-core:2.6.2 and log4j-slf4j-impl:2.2.6 on classpath after upgrading to Spring Boot 1.4.3. The thing is appender is not working for <code>trace</code> level because I am getting log for <code>info</code> or above level.</p>