@Override public void executeEnd(ExecuteContext ctx) {
    Span span = ThreadLocalSpan.CURRENT_TRACER.remove();
    if (span == null || span.isNoop()) return;
    if (ctx.sqlException() != null) span.error(ctx.sqlException());
    span.finish();
  }
Decorates the input such that the {@link RequestContext#current() current request context} and
the and the {@link CurrentTraceContext#get() current trace context} at assembly time is made
current when task is executed.
zipkin-server/src/main/java/zipkin2/server/internal/mysql/ZipkinSelfTracingMySQLStorageConfiguration.java