src/main/java/io/github/glytching/junit/extension/system/SystemPropertyExtension.java
@Override
  public void afterAll(ExtensionContext extensionContext) throws Exception {
    RestoreContext restoreContext = readRestoreContext(extensionContext);
    if (restoreContext != null) {
      restoreContext.restore();
    }
  }
@Override
  public void afterAll(ExtensionContext extensionContext) throws Exception {
    RestoreContext restoreContext = readRestoreContext(extensionContext);
    if (restoreContext != null) {
      restoreContext.restore();
    }
  }
If a {@link RestoreContext} exists for the given {@code extensionContext} then restore it i.e.
unset any system properties which were set in {@link #beforeAll(ExtensionContext)} for this
{@code extensionContext} and reinstate original value, if applicable.

@param extensionContext the <em>context</em> in which the current test or container is being
executed
@throws Exception