fix(core): properly resolve members removal from authoritative groups

- Properly resolve members removal from the last authoritative group
  during the group synchronization.
- We first remove the member from the group, as this should always
  happen, then when all transitive group memberships are resolved
  we ask if there are any remaining authoritative groups and call
  the necessary logic (disabling/removing member).
- This enables use-case when authoritative groups are in hierarchy
  (group structure synchronization).
- Updated javadoc.

perun-core/src/main/java/cz/metacentrum/perun/core/blImpl/GroupsManagerBlImpl.java

@@ -4133,8 +4133,9 @@ private boolean isAuthoritative(PerunSession sess, Group group) throws WrongAttr
 	}
 
 	/**
-	 * Remove member from authoritative group.
-	 * If this is the last authoritative group of this member, delete him from vo, otherwise just disable him in vo.
+	 * Removes member from group which supposed to be authoritative.
+	 * Changes member's status to DISABLED if he was removed from his last authoritative group within the VO.
+	 * If member's previous status was INVALID delete him from VO instead of disabling.
 	 *
 	 * @param sess perun session
 	 * @param group authoritative group
@@ -4144,39 +4145,30 @@ private boolean isAuthoritative(PerunSession sess, Group group) throws WrongAttr
 	 * @throws MemberAlreadyRemovedException if member was already removed
 	 */
 	private void removeMemberFromAuthoritativeGroup(PerunSession sess, Group group, RichMember memberToRemove) throws GroupNotExistsException, NotGroupMemberException, MemberAlreadyRemovedException {
-		List<Group> memberAuthoritativeGroups = null;
-		try {
-			memberAuthoritativeGroups = getAllAuthoritativeGroupsOfMember(sess, memberToRemove);
-		} catch (AttributeNotExistsException ex) {
-			//This means that no authoritative group can exists without this attribute
-			log.error("Attribute {} doesn't exists.", A_G_D_AUTHORITATIVE_GROUP);
-		}
 
-		//If list of member authoritativeGroups is not null, attribute exists
-		if (memberAuthoritativeGroups != null) {
-			memberAuthoritativeGroups.remove(group);
+		// Always remove member from the group
+		getPerunBl().getGroupsManagerBl().removeMember(sess, group, memberToRemove);
+		log.info("Group synchronization {}: Member id {} removed.", group, memberToRemove.getId());
+
+		// Resolve remaining authoritative group memberships
+		try {
+			List<Group> memberAuthoritativeGroups = getAllAuthoritativeGroupsOfMember(sess, memberToRemove);
 			if (memberAuthoritativeGroups.isEmpty()) {
-				//First try to disable member, if is invalid, delete him from Vo
+				// Member is not in any other authoritative group -> disable him
 				try {
 					getPerunBl().getMembersManagerBl().disableMember(sess, memberToRemove);
-					log.debug("Group synchronization {}: Member id {} disabled because synchronizer wants to remove him from last authoritativeGroup in Vo.", group, memberToRemove.getId());
-					getPerunBl().getGroupsManagerBl().removeMember(sess, group, memberToRemove);
-					log.info("Group synchronization {}: Member id {} removed.", group, memberToRemove.getId());
+					log.debug("Group synchronization {}: Member id {} disabled because synchronizer removed him from last authoritative group in Vo.", group, memberToRemove.getId());
 				} catch (MemberNotValidYetException ex) {
-					//Member is still invalid in perun. We can delete him.
+					// Member has INVALID status in VO. We can delete him from VO.
 					getPerunBl().getMembersManagerBl().deleteMember(sess, memberToRemove);
 					log.info("Group synchronization {}: Member id {} would have been disabled but he has been deleted instead because he was invalid and synchronizer wants to remove him from last authoritativeGroup in Vo.", group, memberToRemove.getId());
 				}
-			} else {
-				//If there is still some other authoritative group for this member, only remove him from group
-				getPerunBl().getGroupsManagerBl().removeMember(sess, group, memberToRemove);
-				log.info("Group synchronization {}: Member id {} removed.", group, memberToRemove.getId());
 			}
-			//If list of member authoritativeGroups is null, attribute not exists, only remove member from Group
-		} else {
-			getPerunBl().getGroupsManagerBl().removeMember(sess, group, memberToRemove);
-			log.info("Group synchronization {}: Member id {} removed.", group, memberToRemove.getId());
+		} catch (AttributeNotExistsException ex) {
+			// This means that no authoritative group can exist without this attribute
+			log.error("Attribute {} doesn't exists.", A_G_D_AUTHORITATIVE_GROUP);
 		}
+
 	}
 
 	/**