Allow to remove dependency from MutableProjectDescription

Closes gh-1207

initializr-generator/src/main/java/io/spring/initializr/generator/project/MutableProjectDescription.java

@@ -133,6 +133,10 @@ public Dependency addDependency(String id, Dependency.Builder<?> builder) {
 		return addDependency(id, builder.build());
 	}
 
+	public Dependency removeDependency(String id) {
+		return this.requestedDependencies.remove(id);
+	}
+
 	@Override
 	public Map<String, Dependency> getRequestedDependencies() {
 		return Collections.unmodifiableMap(this.requestedDependencies);

initializr-generator/src/test/java/io/spring/initializr/generator/project/MutableProjectDescriptionTests.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2021 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.spring.initializr.generator.project;
+
+import io.spring.initializr.generator.buildsystem.Dependency;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link MutableProjectDescription}.
+ *
+ * @author Stephane Nicoll
+ */
+class MutableProjectDescriptionTests {
+
+	@Test
+	void removeDependencyWithExistingDependencyReturnsDependency() {
+		MutableProjectDescription description = new MutableProjectDescription();
+		description.addDependency("core", mock(Dependency.class));
+		Dependency testDependency = mock(Dependency.class);
+		description.addDependency("test", testDependency);
+		assertThat(description.removeDependency("test")).isSameAs(testDependency);
+		assertThat(description.getRequestedDependencies()).containsOnlyKeys("core");
+	}
+
+	@Test
+	void removeDependencyWithUnknownDependencyReturnsNull() {
+		MutableProjectDescription description = new MutableProjectDescription();
+		description.addDependency("core", mock(Dependency.class));
+		assertThat(description.removeDependency("unknown")).isNull();
+		assertThat(description.getRequestedDependencies()).containsOnlyKeys("core");
+	}
+
+}