Fix syntax and punctuation, and add test for connectivity warning for…

…mat.

PiperOrigin-RevId: 247976192

src/main/java/com/google/devtools/build/lib/network/ConnectivityStatus.java

@@ -18,9 +18,9 @@
 public final class ConnectivityStatus {
   /** Enumerates common connectivity statuses and their generic short warnings. */
   public enum Status {
-    NO_CREDENTIALS("No credentials."),
-    NO_NETWORK("No internet connection."),
-    NOT_REACHABLE("Service not reachable."),
+    NO_CREDENTIALS("No credentials"),
+    NO_NETWORK("No internet connection"),
+    NOT_REACHABLE("Service not reachable"),
     OK("");
 
     /** Generic warning associated with this status. */
@@ -37,9 +37,9 @@ public enum Status {
   /** Generic category type for this status, which contains a generic warning. */
   public final Status status;
 
-  /** Returns the complete formatted warning for this status. */
-  public String fullWarning() {
-    return status.shortWarning + " " + serviceInfo;
+  @Override
+  public String toString() {
+    return serviceInfo.isEmpty() ? status.shortWarning : status.shortWarning + ": " + serviceInfo;
   }
 
   /**