Add a "warning" section to HELP.md

Closes gh-1006

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/documentation/HelpDocument.java

@@ -18,12 +18,14 @@ package io.spring.initializr.generator.spring.documentation;
 
 import java.io.IOException;
 import java.io.PrintWriter;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
 import io.spring.initializr.generator.io.template.MustacheTemplateRenderer;
+import io.spring.initializr.generator.io.text.BulletedSection;
 import io.spring.initializr.generator.io.text.MustacheSection;
 import io.spring.initializr.generator.io.text.Section;
 
@@ -38,6 +40,8 @@ public class HelpDocument {
 
 	private final MustacheTemplateRenderer templateRenderer;
 
+	private final BulletedSection<String> warnings;
+
 	private final GettingStartedSection gettingStarted;
 
 	private final PreDefinedSection nextSteps;
@@ -46,10 +50,20 @@ public class HelpDocument {
 
 	public HelpDocument(MustacheTemplateRenderer templateRenderer) {
 		this.templateRenderer = templateRenderer;
+		this.warnings = new BulletedSection<>(templateRenderer, "documentation/warnings");
 		this.gettingStarted = new GettingStartedSection(templateRenderer);
 		this.nextSteps = new PreDefinedSection("Next Steps");
 	}
 
+	/**
+	 * Return a section that can be used to inform the user that something happened when
+	 * building this project.
+	 * @return a warnings section rendered as bullet points
+	 */
+	public BulletedSection<String> getWarnings() {
+		return this.warnings;
+	}
+
 	public GettingStartedSection gettingStarted() {
 		return this.gettingStarted;
 	}
@@ -78,16 +92,19 @@ public class HelpDocument {
 	}
 
 	public void write(PrintWriter writer) throws IOException {
-		LinkedList<Section> allSections = new LinkedList<>(this.sections);
+		List<Section> allSections = new ArrayList<>();
-		allSections.addFirst(this.gettingStarted);
+		allSections.add(this.warnings);
-		allSections.addLast(this.nextSteps);
+		allSections.add(this.gettingStarted);
+		allSections.addAll(this.sections);
+		allSections.add(this.nextSteps);
 		for (Section section : allSections) {
 			section.write(writer);
 		}
 	}
 
 	public boolean isEmpty() {
-		return gettingStarted().isEmpty() && this.sections.isEmpty() && nextSteps().isEmpty();
+		return getWarnings().isEmpty() && gettingStarted().isEmpty() && this.sections.isEmpty()
+				&& nextSteps().isEmpty();
 	}
 
 }

initializr-generator-spring/src/main/resources/templates/documentation/warnings.mustache

@@ -0,0 +1,6 @@
+# Read Me First
+The following was discovered as part of building this project:
+
+{{#items}}
+* {{.}}
+{{/items}}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/documentation/HelpDocumentTests.java

@@ -52,6 +52,16 @@ class HelpDocumentTests {
 		assertThat(out).contains("# Test", "");
 	}
 
+	@Test
+	void renderWarnings() {
+		HelpDocument document = new HelpDocument(this.templateRenderer);
+		document.getWarnings().addItem("Invalid groupId '#invalid#'");
+		document.getWarnings().addItem("Invalid package name '#invalid#'");
+		String out = write(document);
+		assertThat(out).contains("# Read Me First", "The following was discovered as part of building this project:",
+				"", "* Invalid groupId '#invalid#'", "* Invalid package name '#invalid#'");
+	}
+
 	@Test
 	void renderLinks() {
 		HelpDocument document = new HelpDocument(this.templateRenderer);