fix: Handle null paths in OpenAPI to prevent NPE

Signed-off-by: Haotian Zhang <928016560@qq.com>

spring-cloud-starter-tencent-polaris-contract/src/main/java/com/tencent/cloud/polaris/contract/PolarisContractReporter.java

@@ -114,7 +114,7 @@ public class PolarisContractReporter implements ApplicationListener<ApplicationR
 					request.setVersion(polarisDiscoveryProperties.getVersion());
 					List<InterfaceDescriptor> interfaceDescriptorList = getInterfaceDescriptorFromSwagger(openAPI);
 					request.setInterfaceDescriptors(interfaceDescriptorList);
-					if (StringUtils.isNotBlank(contextPath)) {
+					if (StringUtils.isNotBlank(contextPath) && openAPI.getPaths() != null) {
 						Paths newPaths = new Paths();
 						for (Map.Entry<String, PathItem> entry : openAPI.getPaths().entrySet()) {
 							newPaths.addPathItem(contextPath + entry.getKey(), entry.getValue());
@@ -154,6 +154,9 @@ public class PolarisContractReporter implements ApplicationListener<ApplicationR
 	private List<InterfaceDescriptor> getInterfaceDescriptorFromSwagger(OpenAPI openAPI) {
 		List<InterfaceDescriptor> interfaceDescriptorList = new ArrayList<>();
 		Paths paths = openAPI.getPaths();
+		if (paths == null) {
+			return interfaceDescriptorList;
+		}
 		for (Map.Entry<String, PathItem> p : paths.entrySet()) {
 			PathItem path = p.getValue();
 			Map<String, Operation> operationMap = getOperationMapFromPath(path);
@@ -162,7 +165,12 @@ public class PolarisContractReporter implements ApplicationListener<ApplicationR
 			}
 			for (Map.Entry<String, Operation> o : operationMap.entrySet()) {
 				InterfaceDescriptor interfaceDescriptor = new InterfaceDescriptor();
-				interfaceDescriptor.setPath(contextPath + p.getKey());
+				if (StringUtils.isNotBlank(contextPath)) {
+					interfaceDescriptor.setPath(contextPath + p.getKey());
+				}
+				else {
+					interfaceDescriptor.setPath(p.getKey());
+				}
 				interfaceDescriptor.setMethod(o.getKey());
 				try {
 					String jsonValue;

spring-cloud-starter-tencent-polaris-contract/src/test/java/com/tencent/cloud/polaris/contract/PolarisContractReporterTest.java

@@ -161,4 +161,26 @@ class PolarisContractReporterTest {
 				.extracting(InterfaceDescriptor::getPath)
 				.allMatch(path -> path.startsWith("/api/"));
 	}
+
+	/**
+	 * Test that null paths in OpenAPI returns an empty descriptor list without NPE.
+	 * When OpenAPI.getPaths() returns null, the method should gracefully return
+	 * an empty list instead of throwing NullPointerException.
+	 */
+	@DisplayName("null paths in OpenAPI returns empty descriptor list")
+	@Test
+	void testNullPathsReturnsEmptyList() throws Exception {
+		// Arrange
+		PolarisContractReporter reporter = new PolarisContractReporter(
+				null, null, polarisContractProperties, providerAPI,
+				polarisDiscoveryProperties, springdocObjectMapperProvider, "/context");
+		OpenAPI openAPI = new OpenAPI();
+		// Do not call openAPI.setPaths(), so getPaths() returns null
+
+		// Act
+		List<InterfaceDescriptor> descriptors = invokeGetInterfaceDescriptorFromSwagger(reporter, openAPI);
+
+		// Assert
+		assertThat(descriptors).isNotNull().isEmpty();
+	}
 }