synchronized ScriptingContainerDelegateImpl getInitialized() {
        if (this.impl == null) {
            this.impl = ScriptingContainerDelegateImpl.create(
                    this.classLoader, this.delegateLocalContextScope, this.delegateLocalVariableBehavior);
            if (this.initializer != null) {
                this.initializer.initialize(this.impl);
                this.logger.info("Loaded JRuby runtime {}", this.impl.getJRubyVersion());
            }
        }
        return this.impl;
    }
Indirects onto JRuby with initializing ScriptingContainer lazily.
embulk-core/src/main/java/org/embulk/jruby/LazyScriptingContainerDelegate.java