[html] Use ModelUtils to avoid NullPointerException (#1948)

Author: jmini

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/StaticHtmlGenerator.java

@@ -194,7 +194,7 @@ public void preprocessOpenAPI(OpenAPI openAPI) {
         Info info = openAPI.getInfo();
         info.setDescription(toHtml(info.getDescription()));
         info.setTitle(toHtml(info.getTitle()));
-        Map<String, Schema> models = openAPI.getComponents().getSchemas();
+        Map<String, Schema> models = ModelUtils.getSchemas(openAPI);
         for (Schema model : models.values()) {
             model.setDescription(toHtml(model.getDescription()));
             model.setTitle(toHtml(model.getTitle()));

modules/openapi-generator/src/test/java/org/openapitools/codegen/html/StaticHtmlGeneratorTest.java

@@ -17,10 +17,13 @@
 
 package org.openapitools.codegen.html;
 
+import io.swagger.parser.OpenAPIParser;
+import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.media.IntegerSchema;
 import io.swagger.v3.oas.models.media.ObjectSchema;
 import io.swagger.v3.oas.models.media.Schema;
 import io.swagger.v3.oas.models.media.StringSchema;
+import io.swagger.v3.parser.core.models.ParseOptions;
 
 import org.openapitools.codegen.CodegenModel;
 import org.openapitools.codegen.languages.StaticHtmlGenerator;
@@ -43,4 +46,14 @@ public void testAdditionalPropertiesFalse() {
         Assert.assertNotNull(cm);
     }
 
+    @Test
+    public void testSpecWithoutSchema() throws Exception {
+        final OpenAPI openAPI = new OpenAPIParser().readLocation("src/test/resources/3_0/ping.yaml", null, new ParseOptions()).getOpenAPI();
+
+        final StaticHtmlGenerator codegen = new StaticHtmlGenerator();
+        codegen.preprocessOpenAPI(openAPI);
+
+        Assert.assertEquals(openAPI.getInfo().getTitle(), "ping test");
+    }
+
 }