Catch missing BouncyCastle PGP during contact store creation

If the class isn't found, we return the dummy store which
is disabled.  This is necessary because PGP installation is
an optional dependency.

Signed-off-by: Shawn O. Pearce <sop@google.com>

src/main/java/com/google/gerrit/server/EncryptedContactStoreProvider.java

@@ -45,19 +45,28 @@ public class EncryptedContactStoreProvider implements Provider<ContactStore> {
   public ContactStore get() {
     try {
       return new EncryptedContactStore(config, sitePath, schema);
+    } catch (NoClassDefFoundError notInstalled) {
+      return noContact(new ContactInformationStoreException(
+          new ClassNotFoundException("BouncyCastle PGP not installed",
+              notInstalled)));
     } catch (final ContactInformationStoreException initError) {
-      return new ContactStore() {
-        @Override
-        public boolean isEnabled() {
-          return false;
-        }
-
-        @Override
-        public void store(Account account, ContactInformation info)
-            throws ContactInformationStoreException {
-          throw initError;
-        }
-      };
+      return noContact(initError);
     }
   }
+
+  private ContactStore noContact(
+      final ContactInformationStoreException initError) {
+    return new ContactStore() {
+      @Override
+      public boolean isEnabled() {
+        return false;
+      }
+
+      @Override
+      public void store(Account account, ContactInformation info)
+          throws ContactInformationStoreException {
+        throw initError;
+      }
+    };
+  }
 }