Move HTTP headers to APICalls.ps1

The Content-Type value is now specified via the Invoke-RestMethod
-ContentType parameter in Internal/APICalls.ps1.

Author: davidhaymond

ITGlueAPI/ITGlueAPI.psm1

@@ -1,6 +1 @@
-$ITGlue_Headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
-$ITGlue_Headers.Add("Content-Type", 'application/vnd.api+json')
-
-Set-Variable -Name "ITGlue_Headers"  -Value $ITGlue_Headers -Scope global
-
-Import-ITGlueModuleSettings
+Import-ITGlueModuleSettings

ITGlueAPI/Internal/APICalls.ps1

@@ -35,12 +35,14 @@ function Invoke-ITGlueRequest {
     }
 
     try {
-        $ITGlue_Headers.Add('x-api-key', (New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList 'N/A', $ITGlue_API_Key).GetNetworkCredential().Password)
+        $headers = @{
+            'x-api-key' = (New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList 'N/A', $ITGlue_API_Key).GetNetworkCredential().Password
+        }
 
         $parameters = @{
             'Method' = $Method
             'Uri' = $ITGlue_Base_URI + $ResourceURI + $query_string
-            'Headers' = $ITGlue_Headers
+            'Headers' = $headers
             'Body' = $body
         }
         if ($Method -ne 'GET') {
@@ -50,8 +52,6 @@ function Invoke-ITGlueRequest {
         $api_response = Invoke-RestMethod @parameters -ErrorAction Stop
     } catch {
         Write-Error $_
-    } finally {
-        [void] ($ITGlue_Headers.Remove('x-api-key')) # Quietly clean up scope so the API key doesn't persist
     }
 
     return $api_response