Extract field generation into its own method.

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -581,7 +581,13 @@ namespace CppSharp.Generators.CSharp
 
             foreach (var field in @class.Fields)
             {
-                if (ASTUtils.CheckIgnoreField(@class, field)) continue;
+                GenerateClassField(@class, isInternal, field);
+            }
+        }
+
+        private void GenerateClassField(Class @class, bool isInternal, Field field)
+        {
+            if (ASTUtils.CheckIgnoreField(@class, field)) return;
 
             PushBlock(CSharpBlockKind.Field);
 
@@ -612,7 +618,6 @@ namespace CppSharp.Generators.CSharp
 
             PopBlock(NewLineKind.BeforeNextBlock);
         }
-        }
 
         #endregion