[java] Support 'duration' format

[Allsimon]

See https://spec.openapis.org/registry/format/duration.html

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---

Summary by cubic

Adds Java support for the OpenAPI duration string format (per https://spec.openapis.org/registry/format/duration.html). Properties with format: duration now generate as java.time.Duration with correct default handling.

• New Features
  • Map duration -> Duration and import java.time.Duration.
  • Parse defaults with Duration.parse(...) when using the java8 date library; otherwise keep the raw string default. Works for nested object defaults too.
  • Added ModelUtils.isDurationSchema, tests, and Spring sample updates to cover generation and defaults.

^{Written for commit 9e782e0. Summary will update on new commits.}

[cubic-dev-ai]

3 issues found across 7 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java">

<violation number="1" location="modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java:1465">
P2: Duration defaults are dropped for `java8-*` variants because this branch only accepts exact `java8` even though `duration` is mapped for all `java8*` libraries.</violation>

<violation number="2" location="modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java:1561">
P2: Nested `duration` properties have the same exact-`java8` gate, so defaults are also dropped for `java8-*` variants.</violation>
</file>

<file name="samples/client/petstore/spring-cloud-date-time/src/main/java/org/openapitools/model/Pet.java">

<violation number="1" location="samples/client/petstore/spring-cloud-date-time/src/main/java/org/openapitools/model/Pet.java:50">
P2: Mapping OpenAPI `duration` to `java.time.Duration` rejects valid RFC3339 duration values with year/month/week components, so payloads like `P1Y` or `P2W` will not deserialize correctly.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: Nested duration properties have the same exact-java8 gate, so defaults are also dropped for java8-* variants.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java, line 1561:

<comment>Nested `duration` properties have the same exact-`java8` gate, so defaults are also dropped for `java8-*` variants.</comment>

<file context>
@@ -1548,6 +1557,10 @@ public String toDefaultValue(CodegenProperty cp, Schema schema) {
                                     defaultPropertyExpression = String.format(Locale.ROOT, "java.time.LocalDateTime.parse(\"%s\")", value.asText());
                                 }
+                            } else if(ModelUtils.isDurationSchema(propertySchema)) {
+                                if("java8".equals(getDateLibrary())) {
+                                    defaultPropertyExpression = String.format(Locale.ROOT, "java.time.Duration.parse(\"%s\")", value.asText());
+                                }
</file context>

[cubic-dev-ai]

P2: Duration defaults are dropped for java8-* variants because this branch only accepts exact java8 even though duration is mapped for all java8* libraries.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractJavaCodegen.java, line 1465:

<comment>Duration defaults are dropped for `java8-*` variants because this branch only accepts exact `java8` even though `duration` is mapped for all `java8*` libraries.</comment>

<file context>
@@ -1458,6 +1460,13 @@ public String toDefaultValue(CodegenProperty cp, Schema schema) {
             return null;
+        } else if (ModelUtils.isDurationSchema(schema)) {
+            if (schema.getDefault() != null) {
+                if ("java8".equals(getDateLibrary())) {
+                    return String.format(Locale.ROOT, "Duration.parse(\"%s\")", schema.getDefault());
+                }
</file context>

[cubic-dev-ai]

P2: Mapping OpenAPI duration to java.time.Duration rejects valid RFC3339 duration values with year/month/week components, so payloads like P1Y or P2W will not deserialize correctly.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At samples/client/petstore/spring-cloud-date-time/src/main/java/org/openapitools/model/Pet.java, line 50:

<comment>Mapping OpenAPI `duration` to `java.time.Duration` rejects valid RFC3339 duration values with year/month/week components, so payloads like `P1Y` or `P2W` will not deserialize correctly.</comment>

<file context>
@@ -46,6 +47,8 @@ public class Pet {
 
   private LocalDateTime adoptionDate = LocalDateTime.parse("2007-12-03T10:15:30");
 
+  private Duration tripDuration = Duration.parse("PT10H15M30S");
+
   public Pet() {
</file context>

[Allsimon]

the bot noticed that duration doesn't deserialize correctly #23695 (comment)

closing this for now