问ClassNotFoundException JavaRecursiveElementVisitor

EN

Caused by: java.lang.ClassNotFoundException: com.intellij.psi.JavaRecursiveElementVisitor PluginClassLoader[com.rahul.gqlformat, 1.0] com.intellij.ide.plugins.cl.PluginClassLoader@2a707a23

package com.rahul.gqlformat;

import com.intellij.openapi.fileEditor.FileEditorManager;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.vfs.VirtualFile;
import com.intellij.openapi.wm.ToolWindow;
import com.intellij.psi.*;

import javax.swing.*;

public class GqlView {
    private JTextArea textArea;
    private JButton btn;
    private JPanel panel;
    private Project project;

    public GqlView(Project project) {
        this.project = project;
        btn.addActionListener(actionEvent -> {
            textArea.append("Hello");
//            printSelectedFileName();
        });

    }


    void printSelectedFileName() {
        FileEditorManager fileEditorManager = FileEditorManager.getInstance(project);
        VirtualFile[] virtualFile = fileEditorManager.getOpenFiles();
        if (virtualFile != null && virtualFile.length > 0) {
            VirtualFile vf = virtualFile[0];
            PsiFile psiFile = PsiManager.getInstance(project).findFile(vf);

            psiFile.accept(new JavaRecursiveElementVisitor() {
                @Override
                public void visitLocalVariable(PsiLocalVariable variable) {
                    super.visitLocalVariable(variable);
                    System.out.println("Found a variable at offset " + variable.getTextRange().getStartOffset());
                }
            });
        }

    }

    public JPanel getPanel() {
        return panel;
    }
}

plugins {
    id 'java'
    id 'org.jetbrains.intellij' version '0.4.21'
    id 'org.jetbrains.kotlin.jvm' version '1.3.72'
}

group 'com.rahul.gqlformal'
version '1.0'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
    testCompile group: 'junit', name: 'junit', version: '4.12'
}

intellij {
    version = '2020.1'
    plugins = ['java']
}


buildSearchableOptions {
    enabled = false
}

patchPluginXml {
    version = project.version
    sinceBuild = '201'
    untilBuild = '201.*'
}