Public/Get-JiraIssueWatcher.ps1

function Get-JiraIssueWatcher {
    # .ExternalHelp ..\JiraPS-help.xml
    [CmdletBinding()]
    param(
        [Parameter( Mandatory, ValueFromPipeline, ValueFromPipelineByPropertyName )]
        [ValidateNotNullOrEmpty()]
        [ValidateScript(
            {
                if (("JiraPS.Issue" -notin $_.PSObject.TypeNames) -and (($_ -isnot [String]))) {
                    $exception = ([System.ArgumentException]"Invalid Type for Parameter") #fix code highlight]
                    $errorId = 'ParameterType.NotJiraIssue'
                    $errorCategory = 'InvalidArgument'
                    $errorTarget = $_
                    $errorItem = New-Object -TypeName System.Management.Automation.ErrorRecord $exception, $errorId, $errorCategory, $errorTarget
                    $errorItem.ErrorDetails = "Wrong object type provided for Issue. Expected [JiraPS.Issue] or [String], but was $($_.GetType().Name)"
                    $PSCmdlet.ThrowTerminatingError($errorItem)
                    <#
                      #ToDo:CustomClass
                      Once we have custom classes, this check can be done with Type declaration
                    #>

                }
                else {
                    return $true
                }
            }
        )]
        [Alias('Key')]
        [Object]
        $Issue,

        [Parameter()]
        [System.Management.Automation.PSCredential]
        [System.Management.Automation.Credential()]
        $Credential = [System.Management.Automation.PSCredential]::Empty
    )

    begin {
        Write-Verbose "[$($MyInvocation.MyCommand.Name)] Function started"
    }

    process {
        Write-DebugMessage "[$($MyInvocation.MyCommand.Name)] ParameterSetName: $($PsCmdlet.ParameterSetName)"
        Write-DebugMessage "[$($MyInvocation.MyCommand.Name)] PSBoundParameters: $($PSBoundParameters | Out-String)"

        # Find the proper object for the Issue
        $issueObj = Resolve-JiraIssueObject -InputObject $Issue -Credential $Credential

        foreach ($issue in $issueObj) {
            $parameter = @{
                URI        = "{0}/watchers" -f $issue.RestURL
                Method     = "GET"
                Credential = $Credential
            }
            Write-Debug "[$($MyInvocation.MyCommand.Name)] Invoking JiraMethod with `$parameter"
            if ($result = Invoke-JiraMethod @parameter) {
                Write-Output $result.watchers
                # TODO: are these users?
            }
        }
    }

    end {
        Write-Verbose "[$($MyInvocation.MyCommand.Name)] Complete"
    }
}