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Merged
wing328 merged 2 commits into from
Oct 4, 2026
Merged

fix(java): serialize JSON header parameter content #25056

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1d2708b
fix(java): serialize JSON header parameter content
AndreyVMarkelov Sep 30, 2026
4d4d313
fix(java): preserve null JSON header semantics
AndreyVMarkelov Oct 4, 2026
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46 changes: 45 additions & 1 deletion modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/ApiClient.mustache
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Original file line number Diff line number Diff line change
Expand Up @@ -912,6 +912,46 @@ public class ApiClient {
}
}

/**
* Format the given parameter object as an ASCII-safe JSON string.
*
* @param param Parameter
* @return JSON representation of the parameter
*/
public String parameterToJsonString(Object param) {
if (param == null) {
return "";
}
String json = JSON.serialize(param);
int firstUnsafe = -1;
for (int i = 0; i < json.length(); i++) {
if (json.charAt(i) >= 0x7f) {
firstUnsafe = i;
break;
}
}
if (firstUnsafe == -1) {
return json;
}

StringBuilder escaped = new StringBuilder(json.length());
escaped.append(json, 0, firstUnsafe);
for (int i = firstUnsafe; i < json.length(); i++) {
char c = json.charAt(i);
if (c >= 0x7f) {
escaped.append("\\u");
escaped.append(Character.forDigit((c >> 12) & 0xf, 16));
escaped.append(Character.forDigit((c >> 8) & 0xf, 16));
escaped.append(Character.forDigit((c >> 4) & 0xf, 16));
escaped.append(Character.forDigit(c & 0xf, 16));
} else {
escaped.append(c);
}
}

return escaped.toString();
}

/**
* Formats the specified query parameter to a list containing a single {@code Pair} object.
*
Expand Down Expand Up @@ -1954,7 +1994,11 @@ public class ApiClient {
}
break;
case "header":
headerParams.put(param.getName(), parameterToString(value));
if (param.getContent() != null && param.getContent().containsKey("application/json")) {
headerParams.put(param.getName(), parameterToJsonString(value));
} else {
headerParams.put(param.getName(), parameterToString(value));
}
break;
case "cookie":
cookieParams.put(param.getName(), parameterToString(value));
Expand Down
5 changes: 5 additions & 0 deletions modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/api.mustache
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Original file line number Diff line number Diff line change
Expand Up @@ -229,7 +229,12 @@ public class {{classname}} {
{{#headerParams}}

if ({{paramName}} != null) {
{{#headerIsJsonMimeType}}
localVarHeaderParams.put("{{baseName}}", localVarApiClient.parameterToJsonString({{paramName}}));
{{/headerIsJsonMimeType}}
{{^headerIsJsonMimeType}}
localVarHeaderParams.put("{{baseName}}", localVarApiClient.parameterToString({{paramName}}));
{{/headerIsJsonMimeType}}
}

{{/headerParams}}
Expand Down
23 changes: 23 additions & 0 deletions modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5362,6 +5362,29 @@ public void testQueryIsJsonMimeType() {
assertTrue(codegenOperation.queryParams.stream().allMatch(p -> p.queryIsJsonMimeType));
}

@Test
public void testHeaderIsJsonMimeType() {
DefaultCodegen codegen = new DefaultCodegen();
final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_1/java/json-header-content.yaml");
codegen.setOpenAPI(openAPI);
String path = "/test";
CodegenOperation codegenOperation = codegen.fromOperation(path, "POST", openAPI.getPaths().get(path).getPost(), null);

assertThat(codegenOperation.headerParams).hasSize(2);

CodegenParameter jsonHeader = codegenOperation.headerParams.stream()
.filter(param -> "X-Json-Arg".equals(param.baseName))
.findFirst()
.orElseThrow();
assertThat(jsonHeader.headerIsJsonMimeType).isTrue();

CodegenParameter plainHeader = codegenOperation.headerParams.stream()
.filter(param -> "X-Plain-Arg".equals(param.baseName))
.findFirst()
.orElseThrow();
assertThat(plainHeader.headerIsJsonMimeType).isFalse();
}

@Test
public void testDefaultOauthIsNotNull() {
final DefaultCodegen codegen = new DefaultCodegen();
Expand Down
54 changes: 54 additions & 0 deletions .../openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -588,6 +588,60 @@ public void testJersey3NullableNullDefaultRemainsUndefined() {
.doesNotContain("JsonNullable.<List<String>>of(null)");
}

@Test
public void testJsonContentHeaderUsesJsonSerialization() {
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final Path output = newTempFolder();
final CodegenConfigurator configurator = new CodegenConfigurator()
.setGeneratorName(JAVA_GENERATOR)
.setLibrary(JavaClientCodegen.OKHTTP_GSON)
.setInputSpec("src/test/resources/3_1/java/json-header-content.yaml")
.setOutputDir(output.toString().replace("\\", "/"));

List<File> files = new DefaultGenerator().opts(configurator.toClientOptInput()).generate();

validateJavaSourceFiles(files);

assertThat(output.resolve("src/main/java/org/openapitools/client/ApiClient.java"))
.content()
.contains("public String parameterToJsonString(Object param)");

assertThat(output.resolve("src/main/java/org/openapitools/client/api/DefaultApi.java"))
.content()
.contains(
"localVarHeaderParams.put(\"X-Json-Arg\", localVarApiClient.parameterToJsonString(xJsonArg));"
)
.doesNotContain(
"localVarHeaderParams.put(\"X-Json-Arg\", localVarApiClient.parameterToString(xJsonArg));"
);
}

@Test
public void testDynamicJsonContentHeaderUsesJsonSerialization() {
final Path output = newTempFolder();
final CodegenConfigurator configurator = new CodegenConfigurator()
.setGeneratorName(JAVA_GENERATOR)
.setLibrary(JavaClientCodegen.OKHTTP_GSON)
.setInputSpec("src/test/resources/3_1/java/json-header-content.yaml")
.addAdditionalProperty("dynamicOperations", true)
.setOutputDir(output.toString().replace("\\", "/"));

List<File> files = new DefaultGenerator().opts(configurator.toClientOptInput()).generate();

validateJavaSourceFiles(files);

assertThat(output.resolve("src/main/java/org/openapitools/client/ApiClient.java"))
.content()
.contains("if (param.getContent() != null && param.getContent().containsKey(\"application/json\")) {")
.contains("public String parameterToJsonString(Object param) {\n if (param == null) {\n return \"\";\n }")
.contains("headerParams.put(param.getName(), parameterToJsonString(value));")
.contains("headerParams.put(param.getName(), parameterToString(value));");

assertThat(output.resolve("src/main/java/org/openapitools/client/api/DefaultApi.java"))
.content()
.contains("paramMap.put(\"X-Json-Arg\", xJsonArg);")
.contains("paramMap.put(\"X-Plain-Arg\", xPlainArg);");
}

@Test
public void testGeneratePingSomeObj() {
final Path output = newTempFolder();
Expand Down
36 changes: 36 additions & 0 deletions modules/openapi-generator/src/test/resources/3_1/java/json-header-content.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
openapi: 3.1.0

info:
title: JSON header repro
version: 1.0.0

paths:
/test:
post:
operationId: testJsonHeader
parameters:
- name: X-Json-Arg
in: header
required: true
content:
application/json:
schema:
$ref: '#/components/schemas/HeaderArg'
- name: X-Plain-Arg
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in: header
schema:
type: string
responses:
'204':
description: OK

components:
schemas:
HeaderArg:
type: object
required:
- path
properties:
path:
type: string

40 changes: 40 additions & 0 deletions ...a/okhttp-gson-user-defined-templates/src/main/java/org/openapitools/client/ApiClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -793,6 +793,46 @@ public String parameterToString(Object param) {
}
}

/**
* Format the given parameter object as an ASCII-safe JSON string.
*
* @param param Parameter
* @return JSON representation of the parameter
*/
public String parameterToJsonString(Object param) {
if (param == null) {
return "";
}
String json = JSON.serialize(param);
int firstUnsafe = -1;
for (int i = 0; i < json.length(); i++) {
if (json.charAt(i) >= 0x7f) {
firstUnsafe = i;
break;
}
}
if (firstUnsafe == -1) {
return json;
}

StringBuilder escaped = new StringBuilder(json.length());
escaped.append(json, 0, firstUnsafe);
for (int i = firstUnsafe; i < json.length(); i++) {
char c = json.charAt(i);
if (c >= 0x7f) {
escaped.append("\\u");
escaped.append(Character.forDigit((c >> 12) & 0xf, 16));
escaped.append(Character.forDigit((c >> 8) & 0xf, 16));
escaped.append(Character.forDigit((c >> 4) & 0xf, 16));
escaped.append(Character.forDigit(c & 0xf, 16));
} else {
escaped.append(c);
}
}

return escaped.toString();
}

/**
* Formats the specified query parameter to a list containing a single {@code Pair} object.
*
Expand Down
40 changes: 40 additions & 0 deletions ...les/client/echo_api/java/okhttp-gson/src/main/java/org/openapitools/client/ApiClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -723,6 +723,46 @@ public String parameterToString(Object param) {
}
}

/**
* Format the given parameter object as an ASCII-safe JSON string.
*
* @param param Parameter
* @return JSON representation of the parameter
*/
public String parameterToJsonString(Object param) {
if (param == null) {
return "";
}
String json = JSON.serialize(param);
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int firstUnsafe = -1;
for (int i = 0; i < json.length(); i++) {
if (json.charAt(i) >= 0x7f) {
firstUnsafe = i;
break;
}
}
if (firstUnsafe == -1) {
return json;
}

StringBuilder escaped = new StringBuilder(json.length());
escaped.append(json, 0, firstUnsafe);
for (int i = firstUnsafe; i < json.length(); i++) {
char c = json.charAt(i);
if (c >= 0x7f) {
escaped.append("\\u");
escaped.append(Character.forDigit((c >> 12) & 0xf, 16));
escaped.append(Character.forDigit((c >> 8) & 0xf, 16));
escaped.append(Character.forDigit((c >> 4) & 0xf, 16));
escaped.append(Character.forDigit(c & 0xf, 16));
} else {
escaped.append(c);
}
}

return escaped.toString();
}

/**
* Formats the specified query parameter to a list containing a single {@code Pair} object.
*
Expand Down
40 changes: 40 additions & 0 deletions .../others/java/okhttp-gson-oneOf-array/src/main/java/org/openapitools/client/ApiClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -697,6 +697,46 @@ public String parameterToString(Object param) {
}
}

/**
* Format the given parameter object as an ASCII-safe JSON string.
*
* @param param Parameter
* @return JSON representation of the parameter
*/
public String parameterToJsonString(Object param) {
if (param == null) {
return "";
}
String json = JSON.serialize(param);
int firstUnsafe = -1;
for (int i = 0; i < json.length(); i++) {
if (json.charAt(i) >= 0x7f) {
firstUnsafe = i;
break;
}
}
if (firstUnsafe == -1) {
return json;
}

StringBuilder escaped = new StringBuilder(json.length());
escaped.append(json, 0, firstUnsafe);
for (int i = firstUnsafe; i < json.length(); i++) {
char c = json.charAt(i);
if (c >= 0x7f) {
escaped.append("\\u");
escaped.append(Character.forDigit((c >> 12) & 0xf, 16));
escaped.append(Character.forDigit((c >> 8) & 0xf, 16));
escaped.append(Character.forDigit((c >> 4) & 0xf, 16));
escaped.append(Character.forDigit(c & 0xf, 16));
} else {
escaped.append(c);
}
}

return escaped.toString();
}

/**
* Formats the specified query parameter to a list containing a single {@code Pair} object.
*
Expand Down
40 changes: 40 additions & 0 deletions ...client/others/java/okhttp-gson-oneOf/src/main/java/org/openapitools/client/ApiClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -697,6 +697,46 @@ public String parameterToString(Object param) {
}
}

/**
* Format the given parameter object as an ASCII-safe JSON string.
*
* @param param Parameter
* @return JSON representation of the parameter
*/
public String parameterToJsonString(Object param) {
if (param == null) {
return "";
}
String json = JSON.serialize(param);
int firstUnsafe = -1;
for (int i = 0; i < json.length(); i++) {
if (json.charAt(i) >= 0x7f) {
firstUnsafe = i;
break;
}
}
if (firstUnsafe == -1) {
return json;
}

StringBuilder escaped = new StringBuilder(json.length());
escaped.append(json, 0, firstUnsafe);
for (int i = firstUnsafe; i < json.length(); i++) {
char c = json.charAt(i);
if (c >= 0x7f) {
escaped.append("\\u");
escaped.append(Character.forDigit((c >> 12) & 0xf, 16));
escaped.append(Character.forDigit((c >> 8) & 0xf, 16));
escaped.append(Character.forDigit((c >> 4) & 0xf, 16));
escaped.append(Character.forDigit(c & 0xf, 16));
} else {
escaped.append(c);
}
}

return escaped.toString();
}

/**
* Formats the specified query parameter to a list containing a single {@code Pair} object.
*
Expand Down
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