Added convenient constructor

Author: artem-v

services-api/src/main/java/io/scalecube/services/auth/ServicePrincipal.java

@@ -1,5 +1,6 @@
 package io.scalecube.services.auth;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Objects;
 import java.util.Set;
@@ -9,6 +10,22 @@ public class ServicePrincipal implements Principal {
   private final String role;
   private final Set<String> permissions;
 
+  /**
+   * Constructor.
+   *
+   * @param role service role
+   * @param permissions service permissions
+   */
+  public ServicePrincipal(String role, String... permissions) {
+    this(role, Set.copyOf(Arrays.asList(permissions)));
+  }
+
+  /**
+   * Constructor.
+   *
+   * @param role service role
+   * @param permissions service permissions
+   */
   public ServicePrincipal(String role, Set<String> permissions) {
     this.role = role;
     this.permissions = permissions;