构建项目时出现以下错误。这是错误

Question

这是我项目中的应用程序build.gradle文件。任何帮助将不胜感激

def localProperties = new Properties()
    def localPropertiesFile = rootProject.file('local.properties')
    if (localPropertiesFile.exists()) {
        localPropertiesFile.withReader('UTF-8') { reader ->
            localProperties.load(reader)
        }
    }
    
    def flutterRoot = localProperties.getProperty('flutter.sdk')
    if (flutterRoot == null) {
        throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
    }
    
    def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
    if (flutterVersionCode == null) {
        flutterVersionCode = '1'
    }
    
    def flutterVersionName = localProperties.getProperty('flutter.versionName')
    if (flutterVersionName == null) {
        flutterVersionName = '1.0'
    }
    
    apply plugin: 'com.android.application'
    apply plugin: 'kotlin-android'
    apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
    
    android {
        compileSdkVersion 28
    
        sourceSets {
            main.java.srcDirs += 'src/main/kotlin'
        }
    
        lintOptions {
            disable 'InvalidPackage'
        }
    
        defaultConfig {
            // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
            applicationId "com.example.Senior"
            minSdkVersion 16
            targetSdkVersion 28
            versionCode flutterVersionCode.toInteger()
            versionName flutterVersionName
        }
    
        buildTypes {
            release {
                // TODO: Add your own signing config for the release build.
                // Signing with the debug keys for now, so `flutter run --release` works.
                signingConfig signingConfigs.debug
            }
        }
    }
    
    flutter {
        source '../..'
    }
    
    dependencies {
        implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
        
    }

如果有人能帮助我解决此问题，我将感到非常高兴，因为过去3天我一直在此工作。我的应用程序build.gradle文件如上所述。谁能告诉我我错过了什么，我该怎么办。