Gradle WAR build may fail due to non-existing "WEB-INF/lib" in exploded WAR directory

[chanseokoh]

In GradleLayerConfigurations, Files.list() may fail if WEB-INF/lib doesn't exist.

    Path libOutputDirectory = explodedWarPath.resolve("WEB-INF/lib");
    try (Stream<Path> dependencyFileStream = Files.list(libOutputDirectory)) {

Caused by: java.nio.file.NoSuchFileException: <...>/jib-war-helloworld-test/build/jib-exploded-war/WEB-INF/lib
        at com.google.cloud.tools.jib.gradle.GradleLayerConfigurations.getForWarProject(GradleLayerConfigurations.java:182)
        at com.google.cloud.tools.jib.gradle.GradleLayerConfigurations.getForProject(GradleLayerConfigurations.java:62)
        at com.google.cloud.tools.jib.gradle.GradleProjectProperties.getForProject(GradleProjectProperties.java:67)

[chanseokoh]

I checked WEB-INF/classes and even WEB-INF may not exist, so we need to check them too.