add context path cookie

src/main/java/gov/usgs/earthquake/nshmp/www/ContextPathCookie.java

+package gov.usgs.earthquake.nshmp.www;
+
+import java.time.Duration;
+
+import org.reactivestreams.Publisher;
+
+import io.micronaut.context.annotation.Requires;
+import io.micronaut.context.annotation.Value;
+import io.micronaut.core.async.publisher.Publishers;
+import io.micronaut.http.HttpMethod;
+import io.micronaut.http.HttpRequest;
+import io.micronaut.http.MutableHttpResponse;
+import io.micronaut.http.annotation.Filter;
+import io.micronaut.http.cookie.Cookie;
+import io.micronaut.http.filter.HttpServerFilter;
+import io.micronaut.http.filter.ServerFilterChain;
+
+/**
+ * Add context path as a cookie for Swagger to use.
+ *
+ * @author U.S. Geological Survey
+ */
+@Requires(property = "micronaut.server.context-path")
+@Filter(methods = { HttpMethod.GET, HttpMethod.HEAD },
+    patterns = { "/**" })
+public class ContextPathCookie implements HttpServerFilter {
+  private final Cookie contextPathCookie;
+
+  ContextPathCookie(@Value("${micronaut.server.context-path}") String contextPath) {
+    this.contextPathCookie = Cookie.of("contextPath", contextPath).maxAge(Duration.ofMinutes(2L));
+  }
+
+  @Override
+  public Publisher<MutableHttpResponse<?>> doFilter(HttpRequest<?> request,
+      ServerFilterChain chain) {
+    return Publishers.map(chain.proceed(request), response -> response.cookie(contextPathCookie));
+  }
+
+}

src/main/java/gov/usgs/earthquake/nshmp/www/services/ServicesUtil.java

@@ -19,9 +19,9 @@ import gov.usgs.earthquake.nshmp.www.meta.Status;
 
 import io.micronaut.http.HttpResponse;
 
-class ServicesUtil {
+public class ServicesUtil {
 
-  static HttpResponse<String> handleError(
+  public static HttpResponse<String> handleError(
       Throwable e,
       String name,
       String url) {