Get-VSTeamBuild -Properties does not add extended property to build object?

[japj]

Steps to reproduce

$b=Get-VSTeamBuild -ProjectName "<some project>" -Definitions <some definition id> -Properties finishTime -Verbose
VERBOSE: Team Module/7.4.0 (Windows) PowerShell/5.1.19041.610
VERBOSE: GET http://someUrl/_apis/build/builds?api-version=5.0&definitions=1337&properties=finishTime with 0-byte payload
VERBOSE: received 85257-byte response of content type application/json; charset=utf-8; api-version=5.0
VERBOSE: return type: System.Management.Automation.PSCustomObject
VERBOSE: @{count=18; value=System.Object[]}

Expected behavior

$b[0].finishTime to exist/be filled

Actual behavior

$b[0].finishTime does not exist

Environment data

OS

• [x] Windows

Server

• [x] Azure DevOps Server 2020 Update 1

Team Module/7.4.0

> Get-VSTeamAPIVersion
PS D:\> Get-VSTeamAPIVersion


Billing                     :
Build                       : 5.0
Core                        : 5.0
DistributedTask             : 5.0-preview
DistributedTaskReleased     :
ExtensionsManagement        : 5.0-preview
Git                         : 5.0
Graph                       :
HierarchyQuery              : 5.0-preview
MemberEntitlementManagement :
Packaging                   : 5.0-preview
Pipelines                   :
Policy                      : 5.0
Processes                   : 5.0-preview
Release                     : 5.0
ServiceEndpoints            : 5.0-preview
TaskGroups                  : 5.0-preview
Tfvc                        : 5.0
VariableGroups              : 5.0-preview
Version                     : AzD2019

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.19041.610
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.19041.610
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1