[Java][Client] Use java8 OffsetDateTime for clients (#7190)

* use java8 OffsetDateTime for clients

* use java8 OffsetDateTime for clients

* fix javadoc

* add javadoc to JavaTimeFormatter.mustache

* add javadoc to JavaTimeFormatter.mustache

* add javadoc to JavaTimeFormatter.mustache

samples/client/petstore/java/webclient/.openapi-generator/FILES

@@ -66,6 +66,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/ServerConfiguration.java
 src/main/java/org/openapitools/client/ServerVariable.java

samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java

@@ -57,6 +57,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.TimeZone;
+import java.time.OffsetDateTime;
 
 import org.openapitools.client.auth.Authentication;
 import org.openapitools.client.auth.HttpBasicAuth;
@@ -65,7 +66,7 @@ import org.openapitools.client.auth.ApiKeyAuth;
 import org.openapitools.client.auth.OAuth;
 
 @javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
-public class ApiClient {
+public class ApiClient extends JavaTimeFormatter {
     public enum CollectionFormat {
         CSV(","), TSV("\t"), SSV(" "), PIPES("|"), MULTI(null);
 
@@ -346,6 +347,8 @@ public class ApiClient {
             return "";
         } else if (param instanceof Date) {
             return formatDate( (Date) param);
+        } else if (param instanceof OffsetDateTime) {
+            return formatOffsetDateTime((OffsetDateTime) param);
         } else if (param instanceof Collection) {
             StringBuilder b = new StringBuilder();
             for(Object o : (Collection<?>) param) {

samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/JavaTimeFormatter.java

@@ -0,0 +1,64 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+package org.openapitools.client;
+
+import java.time.OffsetDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+
+/**
+ * Class that add parsing/formatting support for Java 8+ {@code OffsetDateTime} class.
+ * It's generated for java clients when {@code AbstractJavaCodegen#dateLibrary} specified as {@code java8}.
+ */
+@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen")
+public class JavaTimeFormatter {
+
+    private DateTimeFormatter offsetDateTimeFormatter = DateTimeFormatter.ISO_OFFSET_DATE_TIME;
+
+    /**
+     * Get the date format used to parse/format {@code OffsetDateTime} parameters.
+     * @return DateTimeFormatter
+     */
+    public DateTimeFormatter getOffsetDateTimeFormatter() {
+        return offsetDateTimeFormatter;
+    }
+
+    /**
+     * Set the date format used to parse/format {@code OffsetDateTime} parameters.
+     * @param offsetDateTimeFormatter {@code DateTimeFormatter}
+     */
+    public void setOffsetDateTimeFormatter(DateTimeFormatter offsetDateTimeFormatter) {
+        this.offsetDateTimeFormatter = offsetDateTimeFormatter;
+    }
+
+    /**
+     * Parse the given string into {@code OffsetDateTime} object.
+     * @param str String
+     * @return {@code OffsetDateTime}
+     */
+    public OffsetDateTime parseOffsetDateTime(String str) {
+        try {
+            return OffsetDateTime.parse(str, offsetDateTimeFormatter);
+        } catch (DateTimeParseException e) {
+            throw new RuntimeException(e);
+        }
+    }
+    /**
+     * Format the given {@code OffsetDateTime} object into string.
+     * @param offsetDateTime {@code OffsetDateTime}
+     * @return {@code OffsetDateTime} in string format
+     */
+    public String formatOffsetDateTime(OffsetDateTime offsetDateTime) {
+        return offsetDateTimeFormatter.format(offsetDateTime);
+    }
+}