diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
index 65b06022d29f..45677bb61e6a 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java
@@ -136,6 +136,10 @@ public class DefaultCodegen implements CodegenConfig {
     protected String modelNamePrefix = "", modelNameSuffix = "";
     protected String apiNameSuffix = "Api";
     protected String testPackage = "";
+    /*
+    apiTemplateFiles are for API outputs only (controllers/handlers).
+    API templates may be written multiple times; APIs are grouped by tag and the file is written once per tag group.
+    */
     protected Map<String, String> apiTemplateFiles = new HashMap<String, String>();
     protected Map<String, String> modelTemplateFiles = new HashMap<String, String>();
     protected Map<String, String> apiTestTemplateFiles = new HashMap<String, String>();
@@ -149,6 +153,11 @@ public class DefaultCodegen implements CodegenConfig {
     protected Map<String, Object> additionalProperties = new HashMap<String, Object>();
     protected Map<String, String> serverVariables = new HashMap<String, String>();
     protected Map<String, Object> vendorExtensions = new HashMap<String, Object>();
+    /*
+    Supporting files are those which aren't models, APIs, or docs.
+    These get a different map of data bound to the templates. Supporting files are written once.
+    See also 'apiTemplateFiles'.
+    */
     protected List<SupportingFile> supportingFiles = new ArrayList<SupportingFile>();
     protected List<CliOption> cliOptions = new ArrayList<CliOption>();
     protected boolean skipOverwrite;