Fix Javadoc in DropwizardConnectors (#467)

* Change javadoc to say there must be exactly one application/admin
  port for the "getOnly" methods

src/main/java/org/kiwiproject/dropwizard/util/server/DropwizardConnectors.java

@@ -132,20 +132,20 @@ public static List<Port> getPorts(DefaultServerFactory serverFactory) {
     }
 
     /**
-     * Get the single application port. If there is more than one, throw an exception.
+     * Get the single application port. If there is not exactly one, throw an exception.
      *
      * @param <C> the type of the Dropwizard Configuration
      * @param configuration the Dropwizard configuration
      * @return the single application port
-     * @throws IllegalStateException if there is more than one application port
+     * @throws IllegalStateException if there is not exactly one application port
      */
     public static <C extends Configuration> Port getOnlyApplicationPort(C configuration) {
         var serverFactory = requireDefaultServerFactory(configuration);
         return getOnlyApplicationPort(serverFactory);
     }
 
     /**
-     *  Get the single application port. If there is more than one, throw an exception.
+     *  Get the single application port. If there is not exactly one, throw an exception.
      *
      * @param serverFactory the {@link DefaultServerFactory} to get the single application port from
      * @return the application port
@@ -180,24 +180,24 @@ public static List<Port> getApplicationPorts(DefaultServerFactory serverFactory)
     }
 
     /**
-     * Get the single admin port. If there is more than one, throw an exception.
+     * Get the single admin port. If there is not exactly one, throw an exception.
      *
      * @param <C> the type of the Dropwizard Configuration
      * @param configuration the Dropwizard configuration
      * @return the admin port
-     * @throws IllegalStateException if there is more than one admin port
+     * @throws IllegalStateException if there is not exactly one admin port
      */
     public static <C extends Configuration> Port getOnlyAdminPort(C configuration) {
         var serverFactory = requireDefaultServerFactory(configuration);
         return getOnlyAdminPort(serverFactory);
     }
 
     /**
-     * Get the single admin port. If there is more than one, throw an exception.
+     * Get the single admin port. If there is not exactly one, throw an exception.
      *
      * @param serverFactory the {@link DefaultServerFactory} to get single admin port from
      * @return the admin port
-     * @throws IllegalStateException if there is more than one admin port
+     * @throws IllegalStateException if there is not exactly one admin port
      */
     public static Port getOnlyAdminPort(DefaultServerFactory serverFactory) {
         var adminPorts = getAdminPorts(serverFactory);