public void initialize() {
            initializeUseSelfContainedJarFiles(this.useSelfContainedJarFiles);
            initializeDependencies(this.dependencies);
        }
A singleton class loader to load classes of embulk-core's hidden dependency libraries, such as Jackson.

<p>This class loader is introduced only to control the visibility from plugins, not for customizability.
It is intentionally designed to be a singleton.
embulk-core/src/main/java/org/embulk/EmbulkDependencyClassLoader.java