Gradle Task has not declared any outputs despite executing actions - amazon-s3

Question

i use gradle-wrapper and have Gradle 6.8 installed.
Succesfull Runs:
bash gradlew check
bash gradlew test
Failed Runs:
`
Task :findMainClass FAILED
Caching disabled for task ':findMainClass' because:
Build cache is disabled
Task ':findMainClass' is not up-to-date because:
Task has not declared any outputs despite executing actions.
:findMainClass (Thread[Execution worker for ':',5,main]) completed. Took 0.001 secs.
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':findMainClass'.
'java.io.File org.gradle.api.tasks.SourceSetOutput.getClassesDir()'
`
This is my build.gradle:
`
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:1.5.2.RELEASE")
}
}
ext {
bootVersion = "1.5.2.RELEASE"
}
//apply plugin: 'idea'
apply plugin: 'org.springframework.boot'
repositories {
mavenCentral()
//mavenLocal()
//maven { url "http://repo.springsource.org/snapshot" }
//maven { url "http://repo.springsource.org/milestone" }
maven { url "https://repo.spring.io/libs-snapshot" }
}
dependencies {
implementation group: 'org.springframework.cloud', name: 'spring-cloud-core', version: '1.2.9.RELEASE'
implementation group: 'org.springframework.cloud', name: 'spring-cloud-spring-service-connector', version: '1.2.9.RELEASE'
implementation group: 'org.springframework.cloud', name: 'spring-cloud-cloudfoundry-connector', version: '1.2.9.RELEASE'
implementation "org.springframework.boot:spring-boot-starter-actuator:${bootVersion}"
implementation "org.springframework.boot:spring-boot-starter-tomcat:${bootVersion}"
implementation "org.springframework.boot:spring-boot-starter-web:${bootVersion}"
implementation "org.springframework.boot:spring-boot-starter-data-jpa:${bootVersion}"
implementation "org.springframework.boot:spring-boot-starter-thymeleaf:${bootVersion}"
implementation 'com.amazonaws:aws-java-sdk:1.11.113'
runtimeOnly "org.yaml:snakeyaml:1.18"
runtimeOnly "mysql:mysql-connector-java:6.0.6"
implementation group: 'net.minidev', name: 'json-smart', version: '2.3'
}
task wrapper1(type: Wrapper) {
gradleVersion = '6.0.1'
}
`
and this is my gradle-wrapper.properties:
distributionBase=GRADLE_USER_HOME distributionPath=wrapper/dists distributionUrl=file:///tmp/my-project/gradle-6.8-all.zip zipStoreBase=GRADLE_USER_HOME zipStorePath=wrapper/dists
Can you help me to solve this issue?
I was trying to deploy an cloudfoundry test applciation: https://github.com/cloudfoundry-samples/cf-s3-demo