Stage failing on Jenkins even though the logs says it was successfull

Question

I have a stage in my Jenkins pipeline to generate and publish the javadoc of my application but for some reason when I run it the build fails because of that stage as it is possible to see in the below screenshot

When I consult the log to see what's the problem it says that the task was successful

This is the code in my pipeline for this stage

 stage('Generate and publish Javadoc on Windows') {
            when { expression { env.OS == 'BAT' }}
            steps {
                dir('') {
                    bat 'gradlew.bat javadoc'
                    javadoc javadocDir: 'build/docs/javadoc', keepAll: true
                }
            }
        }

I think this error could be because there is no new things to publish in the javadoc since my application hasn't changed. Could this be it?

How can I fix this problem?