Fix NPE when server url is null (#2628)

Fix #2625

modules/openapi-generator/src/main/java/org/openapitools/codegen/utils/URLPathUtils.java

@@ -21,6 +21,7 @@ import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.servers.Server;
 import io.swagger.v3.oas.models.servers.ServerVariable;
 import io.swagger.v3.oas.models.servers.ServerVariables;
+import org.apache.commons.lang3.StringUtils;
 import org.openapitools.codegen.CodegenConfig;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -55,6 +56,20 @@ public class URLPathUtils {
         if (variables == null) {
             variables = new ServerVariables();
         }
+        if (StringUtils.isNotBlank(url)) {
+            url = extractUrl(server, url, variables);
+            url = sanitizeUrl(url);
+
+            try {
+                return new URL(url);
+            } catch (MalformedURLException e) {
+                LOGGER.warn("Not valid URL: {}. Default to {}.", server.getUrl(), LOCAL_HOST);
+            }
+        }
+        return getDefaultUrl();
+    }
+
+    private static String extractUrl(Server server, String url, ServerVariables variables) {
         Set<String> replacedVariables = new HashSet<>();
         Matcher matcher = VARIABLE_PATTERN.matcher(url);
         while (matcher.find()) {
@@ -79,14 +94,7 @@ public class URLPathUtils {
                 matcher = VARIABLE_PATTERN.matcher(url);
             }
         }
-        url = sanitizeUrl(url);
+        return url;
-
-        try {
-            return new URL(url);
-        } catch (MalformedURLException e) {
-            LOGGER.warn("Not valid URL: {}. Default to {}.", server.getUrl(), LOCAL_HOST);
-            return getDefaultUrl();
-        }
     }
 
     public static String getScheme(OpenAPI openAPI, CodegenConfig config) {
@@ -110,6 +118,7 @@ public class URLPathUtils {
 
     /**
      * Return the port, example value <code>8080</code>
+     *
      * @param url         server url
      * @param defaultPort if the port is not set
      * @return port
@@ -120,6 +129,7 @@ public class URLPathUtils {
 
     /**
      * Return the port, example value <code>8080</code>
+     *
      * @param url         server url
      * @param defaultPort if the port is not set
      * @return port
@@ -134,6 +144,7 @@ public class URLPathUtils {
 
     /**
      * Return the path, example value <code>/abcdef/xyz</code>
+     *
      * @param url         server url
      * @param defaultPath if the path is not empty
      * @return path
@@ -148,6 +159,7 @@ public class URLPathUtils {
 
     /**
      * Get the protocol and the host, example value <code>https://www.abcdef.xyz</code>
+     *
      * @param url server url
      * @return protocolAndHost
      */
@@ -162,6 +174,7 @@ public class URLPathUtils {
 
     /**
      * Return the first complete URL from the OpenAPI specification
+     *
      * @param openAPI current OpenAPI specification
      * @return host
      */

modules/openapi-generator/src/test/java/org/openapitools/codegen/utils/URLPathUtilsTest.java

@@ -30,7 +30,7 @@ import java.util.Arrays;
 public class URLPathUtilsTest {
 
     @Test
-    public void testDefaultValues() throws Exception {
+    public void testDefaultValues() {
         OpenAPI openAPI = new OpenAPI();
         URL serverURL = URLPathUtils.getServerURL(openAPI);
 
@@ -44,7 +44,7 @@ public class URLPathUtilsTest {
     }
 
     @Test
-    public void testUrl() throws Exception {
+    public void testUrl() {
         OpenAPI openAPI = new OpenAPI();
         openAPI.addServersItem(new Server().url("https://abcdef.xyz:9999/some/path"));
         URL serverURL = URLPathUtils.getServerURL(openAPI);
@@ -59,7 +59,7 @@ public class URLPathUtilsTest {
     }
 
     @Test
-    public void testSanitizeUrl() throws Exception {
+    public void testSanitizeUrl() {
         String[][] testData = {
             { "https://abc1.xyz:9999/some/path", "https://abc1.xyz:9999/some/path" },
             { "HTTPS://abc2.xyz:9999/some/path", "https://abc2.xyz:9999/some/path" },
@@ -79,7 +79,7 @@ public class URLPathUtilsTest {
     }
 
     @Test
-    public void testGetServerURLWithVariables() throws Exception {
+    public void testGetServerURLWithVariables() {
         Server s1 = new Server().url("http://localhost:{port}/").variables(new ServerVariables().addServerVariable("port", new ServerVariable()._default("8080").description("the server port")));
         Assert.assertEquals(URLPathUtils.getServerURL(s1).toString(), "http://localhost:8080/");
 
@@ -113,4 +113,12 @@ public class URLPathUtilsTest {
                         .addServerVariable("user", new ServerVariable()._default("{user}")));
         Assert.assertEquals(URLPathUtils.getServerURL(s9).toString(), "https://{user}.example.com/v1");
     }
+
+    @Test
+    public void useDefaultUrlWhenServerUrlIsNull() {
+        Server server = new Server().url(null);
+
+        URL serverURL = URLPathUtils.getServerURL(server);
+        Assert.assertEquals(serverURL.toString(), "http://localhost");
+    }
 }