fix: allow spaces between html function call and back tick (#10523)

fixes #8881

Author: Denis

flow-server/src/main/java/com/vaadin/flow/component/polymertemplate/BundleParser.java

@@ -15,12 +15,6 @@
  */
 package com.vaadin.flow.component.polymertemplate;
 
-import static com.vaadin.flow.server.frontend.FrontendUtils.DEAULT_FLOW_RESOURCES_FOLDER;
-import static com.vaadin.flow.server.frontend.FrontendUtils.FLOW_NPM_PACKAGE_NAME;
-import static elemental.json.JsonType.ARRAY;
-import static elemental.json.JsonType.OBJECT;
-import static elemental.json.JsonType.STRING;
-
 import java.util.Optional;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -39,6 +33,12 @@
 import elemental.json.JsonObject;
 import elemental.json.JsonType;
 
+import static com.vaadin.flow.server.frontend.FrontendUtils.DEAULT_FLOW_RESOURCES_FOLDER;
+import static com.vaadin.flow.server.frontend.FrontendUtils.FLOW_NPM_PACKAGE_NAME;
+import static elemental.json.JsonType.ARRAY;
+import static elemental.json.JsonType.OBJECT;
+import static elemental.json.JsonType.STRING;
+
 /**
  * Parse statistics data provided by webpack.
  *
@@ -84,7 +84,7 @@ public final class BundleParser {
      * end character with <code>;}</code> e.g. <code>';}</code>
      */
     private static final Pattern POLYMER_TEMPLATE_PATTERN = Pattern.compile(
-            "get[\\s]*template\\(\\)[\\s]*\\{[\\s]*return[\\s]*html([\\`\\'\\\"])([\\s\\S]*)\\1;[\\s]*\\}");
+            "get[\\s]*template\\(\\)[\\s]*\\{[\\s]*return[\\s]*html[\\s]*([\\`\\'\\\"])([\\s\\S]*)\\1;[\\s]*\\}");
 
     private static final Pattern NO_TEMPLATE_PATTERN = Pattern.compile(
             "innerHTML[\\s]*=[\\s]*([\\`\\'\\\"])([\\s]*<dom-module\\s+[\\s\\S]*)\\1;");

flow-server/src/test/java/com/vaadin/flow/component/polymertemplate/BundleParserTest.java

@@ -12,6 +12,7 @@
 
 import elemental.json.Json;
 import elemental.json.JsonObject;
+
 import static com.vaadin.flow.server.Constants.VAADIN_SERVLET_RESOURCES;
 
 public class BundleParserTest {
@@ -85,4 +86,12 @@ public void parseTemplateElement_stringContentNotSeenAsComment() {
                 "nats://server:port", natsElement.attr("placeholder"));
 
     }
+
+    @Test
+    public void parseTemplateElement_spacesBetweenHtmlAndTick() {
+        String source = "static get template() { return html    `<div id='bar'></div>`;}";
+        Element element = BundleParser.parseTemplateElement("foo.js", source);
+
+        Assert.assertNotNull(element.getElementById("bar"));
+    }
 }