Use project location to infer the artifactId

On start.spring.io, if you customize the artifactId it creates a zip file
with the same name. The `spring init` command did not have a similar
shortcut.

This commit updates the request to customize the artifactId if none is
set and a custom location was specified. Just as we check for the
presence of a dot to figure out if we have to extract the archive or not,
we check for it to generate an artifactId without an extension.

In practice, `spring init foo` creates a foo directory with a project
whose artifactId is `foo` and `spring init foo.zip` stores a foo.zip
file with the same project (i.e. the artifactId is `foo`).

Closes gh-3714

spring-boot-cli/src/main/java/org/springframework/boot/cli/command/init/ProjectGenerationRequest.java

@@ -324,8 +324,9 @@ class ProjectGenerationRequest {
 			if (this.groupId != null) {
 				builder.setParameter("groupId", this.groupId);
 			}
-			if (this.artifactId != null) {
-				builder.setParameter("artifactId", this.artifactId);
+			String resolvedArtifactId = resolveArtifactId();
+			if (resolvedArtifactId != null) {
+				builder.setParameter("artifactId", resolvedArtifactId);
 			}
 			if (this.version != null) {
 				builder.setParameter("version", this.version);
@@ -405,6 +406,21 @@ class ProjectGenerationRequest {
 		}
 	}
 
+	/**
+	 * Resolve the artifactId to use or {@code null} if it should not be customized.
+	 * @return the artifactId
+	 */
+	protected String resolveArtifactId() {
+		if (this.artifactId != null) {
+			return this.artifactId;
+		}
+		if (this.output != null) {
+			int i = this.output.lastIndexOf('.');
+			return (i == -1 ? this.output : this.output.substring(0, i));
+		}
+		return null;
+	}
+
 	private static void filter(Map<String, ProjectType> projects, String tag,
 			String tagValue) {
 		for (Iterator<Map.Entry<String, ProjectType>> it = projects.entrySet().iterator(); it

spring-boot-cli/src/test/java/org/springframework/boot/cli/command/init/ProjectGenerationRequestTests.java

@@ -139,6 +139,39 @@ public class ProjectGenerationRequestTests {
 				this.request.generateUrl(createDefaultMetadata()));
 	}
 
+	@Test
+	public void outputCustomizeArtifactId() {
+		this.request.setOutput("my-project");
+		assertEquals(
+				createDefaultUrl("?artifactId=my-project&type=test-type"),
+				this.request.generateUrl(createDefaultMetadata()));
+	}
+
+	@Test
+	public void outputArchiveCustomizeArtifactId() {
+		this.request.setOutput("my-project.zip");
+		assertEquals(
+				createDefaultUrl("?artifactId=my-project&type=test-type"),
+				this.request.generateUrl(createDefaultMetadata()));
+	}
+
+	@Test
+	public void outputArchiveWithDotsCustomizeArtifactId() {
+		this.request.setOutput("my.nice.project.zip");
+		assertEquals(
+				createDefaultUrl("?artifactId=my.nice.project&type=test-type"),
+				this.request.generateUrl(createDefaultMetadata()));
+	}
+
+	@Test
+	public void outputDoesNotOverrideCustomArtifactId() {
+		this.request.setOutput("my-project");
+		this.request.setArtifactId("my-id");
+		assertEquals(
+				createDefaultUrl("?artifactId=my-id&type=test-type"),
+				this.request.generateUrl(createDefaultMetadata()));
+	}
+
 	@Test
 	public void buildNoMatch() {
 		InitializrServiceMetadata metadata = readMetadata();