spring-boot: Bean Validation is incorrectly identified as being present on WLP due to a partial leak of its API into the app's class loader

Spring boot 1.5.8. Liberty version:

/opt/Liberty/bin/productInfo version
Product name: WebSphere Application Server
Product version: 17.0.0.2
Product edition: LIBERTY_CORE

I have problems booting on Liberty

WARN org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext - Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'methodValidationPostProcessor' defined in class path resource [org/springframework/boot/autoconfigure/validation/ValidationAutoConfiguration.class]: Unsatisfied dependency expressed through method 'methodValidationPostProcessor' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultValidator' defined in class path resource [org/springframework/boot/autoconfigure/validation/DefaultValidatorConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.validation.beanvalidation.LocalValidatorFactoryBean]: Factory method 'defaultValidator' threw exception; nested exception is java.lang.LinkageError: loading constraint violation when resolving method "javax/validation/Validation.byDefaultProvider()Ljavax/validation/bootstrap/GenericBootstrap;" : loader "com/ibm/ws/classloading/internal/AppClassLoader@a3fad3f0" of class "org/springframework/boot/validation/MessageInterpolatorFactory" and loader "org/eclipse/osgi/internal/loader/EquinoxClassLoader@65505351" of class "javax/validation/Validation" have different types for the method signature

My war contents (alongside other stuff):

unzip -t dropins/myapp.war |grep -i val
    testing: WEB-INF/lib/validation-api-1.1.0.Final.jar   OK
    testing: WEB-INF/lib/hibernate-validator-5.4.1.Final.jar   OK

There seems to be other with the same problem: https://www.cpume.com/question/fhfsooff-spring-boot-jpa-applicationeventmulticaster-not-initialized-issue.html