@Nullable
    default Boolean verboseResponses() {
        return null;
    }
Returns whether the verbose response mode is enabled. When enabled, the server responses will contain
the exception type and its full stack trace, which may be useful for debugging while potentially
insecure. When disabled, the server responses will not expose such server-side details to the client.

<p>This flag is disabled by default. Specify the {@code -Dcom.linecorp.armeria.verboseResponses=true}
JVM option or use {@link ServerBuilder#verboseResponses(boolean)} to enable it.
core/src/main/java/com/linecorp/armeria/common/FlagsProvider.java