extra loggng and error wraps (#2155)

## Description

Adds info logging on all throttling responses,
and some extra error handling in container
resolvers.

## Does this PR need a docs update or release note?

- [x] ⛔ No 

## Type of change

- [x] 🧹 Tech Debt/Cleanup

## Test Plan

- [x] 💪 Manual

src/internal/connector/exchange/contact_folder_cache.go

@@ -26,15 +26,13 @@ func (cfc *contactFolderCache) populateContactRoot(
 ) error {
 	f, err := cfc.getter.GetContainerByID(ctx, cfc.userID, directoryID)
 	if err != nil {
-		return errors.Wrapf(
+		return support.ConnectorStackErrorTraceWrap(err, "fetching root folder")
-			err,
-			"fetching root contact folder: "+support.ConnectorStackErrorTrace(err))
 	}
 
 	temp := graph.NewCacheFolder(f, path.Builder{}.Append(baseContainerPath...))
 
 	if err := cfc.addFolder(temp); err != nil {
-		return errors.Wrap(err, "adding cache root")
+		return errors.Wrap(err, "adding resolver dir")
 	}
 
 	return nil
@@ -50,16 +48,16 @@ func (cfc *contactFolderCache) Populate(
 	baseContainerPather ...string,
 ) error {
 	if err := cfc.init(ctx, baseID, baseContainerPather); err != nil {
-		return err
+		return errors.Wrap(err, "initializing")
 	}
 
 	err := cfc.enumer.EnumerateContainers(ctx, cfc.userID, baseID, cfc.addFolder)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "enumerating containers")
 	}
 
 	if err := cfc.populatePaths(ctx); err != nil {
-		return errors.Wrap(err, "contacts resolver")
+		return errors.Wrap(err, "populating paths")
 	}
 
 	return nil

src/internal/connector/exchange/event_calendar_cache.go

@@ -31,7 +31,7 @@ func (ecc *eventCalendarCache) Populate(
 
 	err := ecc.enumer.EnumerateContainers(ctx, ecc.userID, "", ecc.addFolder)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "enumerating containers")
 	}
 
 	return nil
@@ -41,20 +41,20 @@ func (ecc *eventCalendarCache) Populate(
 // @returns error iff the required values are not accessible.
 func (ecc *eventCalendarCache) AddToCache(ctx context.Context, f graph.Container) error {
 	if err := checkIDAndName(f); err != nil {
-		return errors.Wrap(err, "adding cache folder")
+		return errors.Wrap(err, "validating container")
 	}
 
 	temp := graph.NewCacheFolder(f, path.Builder{}.Append(*f.GetDisplayName()))
 
 	if err := ecc.addFolder(temp); err != nil {
-		return errors.Wrap(err, "adding cache folder")
+		return errors.Wrap(err, "adding container")
 	}
 
 	// Populate the path for this entry so calls to PathInCache succeed no matter
 	// when they're made.
 	_, err := ecc.IDToPath(ctx, *f.GetId())
 	if err != nil {
-		return errors.Wrap(err, "adding cache entry")
+		return errors.Wrap(err, "setting path to container id")
 	}
 
 	return nil

src/internal/connector/exchange/mail_folder_cache.go

@@ -35,7 +35,7 @@ func (mc *mailFolderCache) populateMailRoot(
 
 		f, err := mc.getter.GetContainerByID(ctx, mc.userID, fldr)
 		if err != nil {
-			return errors.Wrap(err, "fetching root folder"+support.ConnectorStackErrorTrace(err))
+			return support.ConnectorStackErrorTraceWrap(err, "fetching root folder")
 		}
 
 		if fldr == DefaultMailFolder {
@@ -44,7 +44,7 @@ func (mc *mailFolderCache) populateMailRoot(
 
 		temp := graph.NewCacheFolder(f, path.Builder{}.Append(directory))
 		if err := mc.addFolder(temp); err != nil {
-			return errors.Wrap(err, "initializing mail resolver")
+			return errors.Wrap(err, "adding resolver dir")
 		}
 	}
 
@@ -62,16 +62,16 @@ func (mc *mailFolderCache) Populate(
 	baseContainerPath ...string,
 ) error {
 	if err := mc.init(ctx); err != nil {
-		return err
+		return errors.Wrap(err, "initializing")
 	}
 
 	err := mc.enumer.EnumerateContainers(ctx, mc.userID, "", mc.addFolder)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "enumerating containers")
 	}
 
 	if err := mc.populatePaths(ctx); err != nil {
-		return errors.Wrap(err, "mail resolver")
+		return errors.Wrap(err, "populating paths")
 	}
 
 	return nil

src/internal/connector/graph/service_helper.go

@@ -1,7 +1,7 @@
 package graph
 
 import (
-	nethttp "net/http"
+	"net/http"
 	"net/http/httputil"
 	"os"
 	"strings"
@@ -47,7 +47,7 @@ func CreateAdapter(tenant, client, secret string) (*msgraphsdk.GraphRequestAdapt
 }
 
 // CreateHTTPClient creates the httpClient with middlewares and timeout configured
-func CreateHTTPClient() *nethttp.Client {
+func CreateHTTPClient() *http.Client {
 	clientOptions := msgraphsdk.GetDefaultClientOptions()
 	middlewares := msgraphgocore.GetDefaultMiddlewaresWithOptions(&clientOptions)
 	middlewares = append(middlewares, &LoggingMiddleware{})
@@ -67,8 +67,8 @@ type LoggingMiddleware struct{}
 func (handler *LoggingMiddleware) Intercept(
 	pipeline khttp.Pipeline,
 	middlewareIndex int,
-	req *nethttp.Request,
+	req *http.Request,
-) (*nethttp.Response, error) {
+) (*http.Response, error) {
 	var (
 		ctx       = req.Context()
 		resp, err = pipeline.Next(req, middlewareIndex)
@@ -82,6 +82,11 @@ func (handler *LoggingMiddleware) Intercept(
 		return resp, err
 	}
 
+	// special case for supportability: log all throttling cases.
+	if resp.StatusCode == http.StatusTooManyRequests {
+		logger.Ctx(ctx).Infow("graph api throttling", "method", req.Method, "url", req.URL)
+	}
+
 	if logger.DebugAPI || os.Getenv(logGraphRequestsEnvKey) != "" {
 		respDump, _ := httputil.DumpResponse(resp, true)
 

src/internal/connector/support/errors.go

@@ -89,8 +89,20 @@ func concatenateStringFromPointers(orig string, pointers []*string) string {
 	return orig
 }
 
-// ConnectorStackErrorTrace is a helper function that wraps the
+// ConnectorStackErrorTraceWrap is a helper function that wraps the
-// stack trace for oDataError types from querying the M365 back store.
+// stack trace for oDataErrors (if the error has one) onto the prefix.
+// If no stack trace is found, wraps the error with only the prefix.
+func ConnectorStackErrorTraceWrap(e error, prefix string) error {
+	cset := ConnectorStackErrorTrace(e)
+	if len(cset) > 0 {
+		return errors.Wrap(e, prefix+": "+cset)
+	}
+
+	return errors.Wrap(e, prefix)
+}
+
+// ConnectorStackErrorTracew is a helper function that extracts
+// the stack trace for oDataErrors, if the error has one.
 func ConnectorStackErrorTrace(e error) string {
 	eMessage := ""