Java 无法设置未知属性'；s'；对于com.android.build.gradle.internal.api.DefaultAndroidSourceSet类型的源集main

在android Studio中，当我尝试构建项目时，我遇到了一个问题：无法为com.android.build.gradle.internal.api.DefaultAndroidSourceSet类型的源集合main设置未知属性 未知属性是app的build.gradle文件中的java.srcDir s=[app/src/main/java]。该文件的代码如下所示：

apply plugin: 'com.android.application'

apply plugin: 'kotlin-android'

apply plugin: 'kotlin-android-extensions'


android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "com.example.admin.myprofile"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    sourceSets {
        main {
            java.srcDir s =['app/src/main/java']
} }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.2.41"
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.android.support:gridlayout-v7:26.1.0'
    implementation 'com.google.android.gms:play-services-ads:15.0.1'
}

---

java.srcDirs=['app/src/main/java']

=>

java.srcDirs=['app/src/main/java']

java.srcDirs=['app/src/main/java']

java.srcDirs=['app/src/main/java']