title: Remove Log4j and use Logback
body: <p>Is it possible to use Logback instead of Log4j? I have excluded the log4j dependencies from all my projects grade files but when I build the nodes log4j still gets brought in from Corda-core.</p>
  
  <p>Below is how I excluded the dependencies in gradle.</p>
  
  <pre><code>configurations.all {
    exclude group: 'org.apache.logging.log4j', module: 'log4j-api'
    exclude group: 'org.apache.logging.log4j', module: 'log4j-core'
    exclude group: 'org.apache.logging.log4j', module: 'log4j-slf4j-impl'
    exclude group: "org.slf4j", module: "jcl-over-slf4j"
    exclude group: 'org.apache.logging.log4j', module: 'log4j-web'
  }
  </code></pre>
  
  <p>I then added logback as a dependency</p>
  
  <pre><code>compile group: 'ch.qos.logback', name: 'logback-classic', version: '1.2.3'
  </code></pre>
  
  <p>But after deploying the nodes and starting them up I can see that they still use the log4j logger factory.</p>
  
  <pre><code>    SLF4J: Class path contains multiple SLF4J bindings.
  SLF4J: Found binding in [jar:file:/Users/daniel.newton/.capsule/apps/net.corda.node.Corda_3.1-corda/log4j-slf4j-impl-2.9.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
  SLF4J: Found binding in [jar:file:/Users/daniel.newton/dev/projects/corda/build/nodes/party/cordapps/trade-input-cordapp-1.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]
  SLF4J: Found binding in [jar:file:/Users/daniel.newton/dev/projects/corda/build/nodes/party/cordapps/common-1.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]
  SLF4J: Found binding in [jar:file:/Users/daniel.newton/dev/projects/corda/build/nodes/party/cordapps/corda-1.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]
  SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
  SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
  </code></pre>
  
  <p>These log lines suggest that logback has not even been found.</p>
  
  <p>One extra piece of information is that, when I run the tests that exist within in one of the same projects as the cordapps below runs fine and picks up logback successfully but running the nodes does not.</p>