refactor(pdfburner): simplify form field handling and improve default field naming

- Replaced ImmutableDictionary-based FormFieldIndex with a simpler Dictionary
- Updated form field ordering to: NoName, signature, position, city, date
- Removed manual formFieldIndex counter, now using dictionary lookup by fieldName
- Introduced FieldNames class with NoName constant (guid-based) for unnamed fields
- Defaulted Annotation.fieldName to FieldNames.NoName instead of Nothing

EnvelopeGenerator.CommonServices/Jobs/FinalizeDocument/PDFBurner.vb

@@ -1,11 +1,12 @@
-Imports System.Drawing
+Imports System.Collections.Immutable
+Imports System.Drawing
 Imports System.IO
+Imports DevExpress.DataProcessing
 Imports DigitalData.Modules.Base
 Imports DigitalData.Modules.Logging
+Imports EnvelopeGenerator.CommonServices.Jobs.FinalizeDocument.FinalizeDocumentExceptions
 Imports GdPicture14
 Imports Newtonsoft.Json
-Imports EnvelopeGenerator.CommonServices.Jobs.FinalizeDocument.FinalizeDocumentExceptions
-Imports DevExpress.DataProcessing
 
 Namespace Jobs.FinalizeDocument
     Public Class PDFBurner
@@ -68,6 +69,14 @@ Namespace Jobs.FinalizeDocument
             End Using
         End Function
 
+        Public Shared ReadOnly FormFieldIndex As New Dictionary(Of String, Integer) From {
+                {FieldNames.NoName, 0},
+                {"signature", 1},
+                {"position", 2},
+                {"city", 3},
+                {"date", 4}
+            }
+
         Private Sub AddInstantJSONAnnotationToPDF(pInstantJSON As String)
             Dim oAnnotationData = JsonConvert.DeserializeObject(Of AnnotationData)(pInstantJSON)
 
@@ -75,7 +84,6 @@ Namespace Jobs.FinalizeDocument
             Dim yPosOfSigAnnot = oAnnotationData.annotations.ElementAt(2).bbox.ElementAt(1) - 71.84002685546875 + 7
             Dim isSeal = True   'First element is signature seal
 
-            Dim formFieldIndex = 0
             For Each oAnnotation In oAnnotationData.annotations
                 Logger.Debug("Adding AnnotationID: " + oAnnotation.id)
 
@@ -97,13 +105,13 @@ Namespace Jobs.FinalizeDocument
                         'Add form field values
                         Dim formFieldValue = oAnnotationData.formFieldValues.FirstOrDefault(Function(fv) fv.name = oAnnotation.id)
                         If formFieldValue IsNot Nothing AndAlso Not _pdfBurnerParams.IgnoredLabels.Contains(formFieldValue.value) Then
-                            AddFormFieldValue(oAnnotation, formFieldValue, formFieldIndex)
-                            formFieldIndex += 1
+                            AddFormFieldValue(oAnnotation, formFieldValue)
                         End If
                         Exit Select
                 End Select
 
                 isSeal = False
+
             Next
 
         End Sub
@@ -138,12 +146,15 @@ Namespace Jobs.FinalizeDocument
             Next
         End Function
 
-        Private Function AddFormFieldValue(pAnnotation As Annotation, formFieldValue As FormFieldValue, index As Integer) As Void
+        Private Function AddFormFieldValue(pAnnotation As Annotation, formFieldValue As FormFieldValue) As Void
+
+            Dim index As Integer = FormFieldIndex(pAnnotation.fieldName)
+
             ' Convert pixels to Inches
             Dim oBounds = pAnnotation.bbox.Select(AddressOf ToInches).ToList()
 
             Dim oX = oBounds.Item(0)
-            Dim oY = oBounds.Item(1) + _pdfBurnerParams.YOffset * index + _pdfBurnerParams.TopMargin
+            Dim oY = oBounds.Item(1) + _pdfBurnerParams.YOffset * Index + _pdfBurnerParams.TopMargin
             Dim oWidth = oBounds.Item(2)
             Dim oHeight = oBounds.Item(3)
 
@@ -206,10 +217,21 @@ Namespace Jobs.FinalizeDocument
 
             Public index As Integer = Nothing
 
-            Public internalType As String = Nothing
+            Public fieldName As String = FieldNames.NoName
 
             Public hasStructuredID As Boolean = False
 
+            Public ReadOnly Property isLabel As Boolean
+                Get
+                    If String.IsNullOrEmpty(fieldName) Then
+                        Return False
+                    End If
+
+                    Dim parts As String() = fieldName.Split("_"c)
+                    Return parts.Length > 1 AndAlso parts(1) = "label"
+                End Get
+            End Property
+
             Public Property id As String
                 Get
                     Return _id
@@ -240,21 +262,31 @@ Namespace Jobs.FinalizeDocument
                         Throw New BurnAnnotationException($"The index of annotation is not integer. Id: {_id}")
                     End If
 
-                    internalType = parts(3)
+                    fieldName = parts(3)
 
                     hasStructuredID = True
                 End Set
             End Property
 
             Public Property bbox As List(Of Double)
+
             Public Property type As String
+
             Public Property isSignature As Boolean
+
             Public Property imageAttachmentId As String
+
             Public Property lines As Lines
+
             Public Property pageIndex As Integer
+
             Public Property strokeColor As String
         End Class
 
+        Public Class FieldNames
+            Public Shared ReadOnly NoName As String = Guid.NewGuid().ToString()
+        End Class
+
         Friend Class Lines
             Public Property points As List(Of List(Of List(Of Single)))
         End Class