HostnameCache executorService not shut down #1756

Platform:

• Android -> If yes, which Device API (and compileSdkVersion/targetSdkVersion/Build tools) version?
• Java -> If yes, which Java (and sourceCompatibility/targetCompatibility) version? 11
• Kotlin -> If yes, which Kotlin (and jvmTarget) version?
• NDK -> If yes, which NDK/CMake version?
• React-Native -> If yes, which version?
• Timber -> If yes, which version?
• Log4j2 -> If yes, which version?
• Logback -> If yes, which version?
• Spring -> If yes, which version?

IDE:

• Android Studio -> If yes, which version?
• IntelliJ -> If yes, which version?
• Other -> If yes, which one?

Build system:

• Gradle -> If yes, which version?
• Buck -> If yes, which version?
• Bazel -> If yes, which version?
• Maven -> If yes, which version?
• Other -> If yes, which one?

Android Gradle Plugin:

• Yes -> If yes, which version?
• No

Sentry Android Gradle Plugin:

• Yes -> If yes, which version?
• No

Proguard/R8:

• Enabled
• Disabled

Platform installed with:

• JCenter
• Bintray
• Maven Central
• Manually

The version of the SDK:
3.1.2

I have the following issue:

SentryHostNameCache threads not closed after a web application is undeployed in a servlet container.

Steps to reproduce:

Deploy a web app using Sentry into a servlet container

Actual result:

SentryHostNameCache threads not closed

Expected result:

Calling Sentry.close(); should shutdown HostNameCache#executorService. Maybe even sentry-servlet could close Sentry stuff automatically using a ServletContextListener?