Java: Optimize HashSet Initialization (#21205)

* Optimize HashSet Initialization

Noticed this while debugging - we can avoid wasting memory/cpu creating 16 buckets when we only need one or a few.

* generate samples

* use Arrays.asList

Author: winrid

modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/pojo.mustache

@@ -322,16 +322,20 @@ public class {{classname}} {{#parent}}extends {{{.}}} {{/parent}}{{#vendorExtens
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
-    {{#allVars}}
-    openapiFields.add("{{baseName}}");
-    {{/allVars}}
+    {{#hasVars}}
+    openapiFields = new HashSet<String>(Arrays.asList({{#allVars}}"{{baseName}}"{{^-last}}, {{/-last}}{{/allVars}}));
+    {{/hasVars}}
+    {{^hasVars}}
+    openapiFields = new HashSet<String>(0);
+    {{/hasVars}}
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
-    {{#requiredVars}}
-    openapiRequiredFields.add("{{baseName}}");
-    {{/requiredVars}}
+    {{#hasRequired}}
+    openapiRequiredFields = new HashSet<String>(Arrays.asList({{#requiredVars}}"{{baseName}}"{{^-last}}, {{/-last}}{{/requiredVars}}));
+    {{/hasRequired}}
+    {{^hasRequired}}
+    openapiRequiredFields = new HashSet<String>(0);
+    {{/hasRequired}}
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/modelCopy/Category.java

@@ -71,10 +71,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
+    openapiFields = new HashSet<String>(0);
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/modelCopy/ModelApiResponse.java

@@ -71,10 +71,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
+    openapiFields = new HashSet<String>(0);
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/modelCopy/Order.java

@@ -71,10 +71,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
+    openapiFields = new HashSet<String>(0);
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/modelCopy/Pet.java

@@ -71,10 +71,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
+    openapiFields = new HashSet<String>(0);
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/modelCopy/Tag.java

@@ -71,10 +71,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
+    openapiFields = new HashSet<String>(0);
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/modelCopy/User.java

@@ -71,10 +71,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
+    openapiFields = new HashSet<String>(0);
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/src/main/java/org/openapitools/client/model/Category.java

@@ -147,12 +147,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
-    openapiFields.add("id");
-    openapiFields.add("name");
+    openapiFields = new HashSet<String>(Arrays.asList("id", "name"));
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/src/main/java/org/openapitools/client/model/ModelApiResponse.java

@@ -173,13 +173,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
-    openapiFields.add("code");
-    openapiFields.add("type");
-    openapiFields.add("message");
+    openapiFields = new HashSet<String>(Arrays.asList("code", "type", "message"));
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**

samples/client/echo_api/java/okhttp-gson-user-defined-templates/src/main/java/org/openapitools/client/model/Order.java

@@ -306,16 +306,10 @@ private String toIndentedString(Object o) {
 
   static {
     // a set of all properties/fields (JSON key names)
-    openapiFields = new HashSet<String>();
-    openapiFields.add("id");
-    openapiFields.add("petId");
-    openapiFields.add("quantity");
-    openapiFields.add("shipDate");
-    openapiFields.add("status");
-    openapiFields.add("complete");
+    openapiFields = new HashSet<String>(Arrays.asList("id", "petId", "quantity", "shipDate", "status", "complete"));
 
     // a set of required properties/fields (JSON key names)
-    openapiRequiredFields = new HashSet<String>();
+    openapiRequiredFields = new HashSet<String>(0);
   }
 
   /**