Fix loading of static resources from the class path

core/src/main/java/io/smallrye/openapi/api/SmallRyeOpenAPI.java

@@ -541,7 +541,13 @@ protected void buildReaderModel(BuildContext<?, ?, ?, ?, ?> ctx) {
         protected <V, A extends V, O extends V, AB, OB> void buildStaticModel(BuildContext<V, A, O, AB, OB> ctx) {
             if (enableStandardStaticFiles) {
                 Function<String, URL> loadFn = Optional.ofNullable(resourceLocator)
-                        .orElse(ctx.appClassLoader::getResource);
+                        .orElse(path -> {
+                            StringBuilder loadPath = new StringBuilder(path);
+                            if (loadPath.charAt(0) == '/') {
+                                loadPath.delete(0, 1);
+                            }
+                            return ctx.appClassLoader.getResource(loadPath.toString());
+                        });
 
                 ctx.staticModel = OpenApiProcessor.loadOpenApiStaticFiles(loadFn)
                         .stream()

core/src/test/java/io/smallrye/openapi/api/SmallRyeOpenAPIBuilderTest.java

@@ -0,0 +1,38 @@
+package io.smallrye.openapi.api;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.net.URL;
+import java.net.URLClassLoader;
+
+import org.eclipse.microprofile.openapi.models.OpenAPI;
+import org.junit.jupiter.api.Test;
+
+class SmallRyeOpenAPIBuilderTest {
+
+    @Test
+    void testStaticFileLoadedFromClasspath() throws Exception {
+        URL loaderRoot = getClass()
+                .getClassLoader()
+                .getResource("classloader/META-INF/openapi.yaml")
+                .toURI()
+                .resolve("..")
+                .toURL();
+
+        ClassLoader custom = new URLClassLoader(
+                new URL[] { loaderRoot },
+                Thread.currentThread().getContextClassLoader());
+
+        SmallRyeOpenAPI result = SmallRyeOpenAPI.builder()
+                .withApplicationClassLoader(custom)
+                .enableModelReader(false)
+                .enableStandardFilter(false)
+                .enableAnnotationScan(false)
+                .enableStandardStaticFiles(true)
+                .build();
+
+        OpenAPI model = result.model();
+        assertEquals("Loaded from the class path", model.getInfo().getTitle());
+    }
+
+}

core/src/test/resources/classloader/META-INF/openapi.yaml

@@ -0,0 +1,6 @@
+---
+openapi: 3.1.0
+info:
+  title: Loaded from the class path
+  version: "1.0.0"
+paths: {}

tools/maven-plugin/src/test/java/io/smallrye/openapi/mavenplugin/BasicIT.java

@@ -44,6 +44,7 @@ void basic_info(MavenExecutionResult result) throws IOException {
             assertEquals(properties.get("infoContactUrl"), schema.getInfo().getContact().getUrl());
             assertEquals(properties.get("infoContactEmail"), schema.getInfo().getContact().getEmail());
             assertEquals(properties.get("infoLicenseName"), schema.getInfo().getLicense().getName());
+            assertEquals("My Custom Extension", schema.getInfo().getExtensions().get("x-custom-extension"));
             assertEquals(properties.get("infoLicenseIdentifier"),
                     schema.getInfo().getLicense().getIdentifier());
             //The URL is not tested here due to being exclusive with Identifier

tools/maven-plugin/src/test/resources-its/io/smallrye/openapi/mavenplugin/BasicIT/basic_info/src/main/resources/META-INF/openapi.yaml

@@ -0,0 +1,3 @@
+openapi: "3.0.3"
+info:
+  x-custom-extension: My Custom Extension