Allow snapshot repository for samples

When a release is published Spring Boot has not been released, so
it can be beneficial to allow the samples to use the snapshot
repository. This is determined based on the springBootVersion property.

Author: rwinch

buildSrc/src/main/groovy/io/spring/gradle/convention/AbstractSpringJavaPlugin.groovy

@@ -35,6 +35,7 @@ public abstract class AbstractSpringJavaPlugin implements Plugin<Project> {
 
 	@Override
 	public final void apply(Project project) {
+		initialPlugins(project);
 		PluginManager pluginManager = project.getPluginManager();
 		pluginManager.apply(JavaPlugin.class);
 		pluginManager.apply(ManagementConfigurationPlugin.class)
@@ -69,5 +70,7 @@ public abstract class AbstractSpringJavaPlugin implements Plugin<Project> {
 		additionalPlugins(project);
 	}
 
+	protected void initialPlugins(Project project) {}
+
 	protected abstract void additionalPlugins(Project project);
 }

buildSrc/src/main/groovy/io/spring/gradle/convention/SpringSamplePlugin.groovy

@@ -30,4 +30,19 @@ public class SpringSamplePlugin extends AbstractSpringJavaPlugin {
             project.sonarqube.skipProject = true
         }
     }
+
+	@Override
+	protected void initialPlugins(Project project) {
+		if (project.hasProperty('springBootVersion')) {
+			String springBootVersion = project.springBootVersion
+
+			if (Utils.isSnapshot(springBootVersion)) {
+				project.ext.forceMavenRepositories = 'snapshot'
+			}
+			else if (Utils.isMilestone(springBootVersion)) {
+				project.ext.forceMavenRepositories = 'milestone'
+			}
+		}
+
+	}
 }

buildSrc/src/main/groovy/io/spring/gradle/convention/Utils.groovy

@@ -14,16 +14,29 @@ public class Utils {
 
 	static boolean isSnapshot(Project project) {
 		String projectVersion = projectVersion(project)
-		return projectVersion.matches('^.*([.-]BUILD)?-SNAPSHOT$')
+		return isSnapshot(projectVersion)
 	}
 
 	static boolean isMilestone(Project project) {
 		String projectVersion = projectVersion(project)
-		return projectVersion.matches('^.*[.-]M\\d+$') || projectVersion.matches('^.*[.-]RC\\d+$')
+		return isMilestone(projectVersion)
 	}
 
 	static boolean isRelease(Project project) {
-		return !(isSnapshot(project) || isMilestone(project))
+		String projectVersion = projectVersion(project)
+		return isRelease(projectVersion)
+	}
+
+	static boolean isSnapshot(String projectVersion) {
+		return projectVersion.matches('^.*([.-]BUILD)?-SNAPSHOT$')
+	}
+
+	static boolean isMilestone(String projectVersion) {
+		return projectVersion.matches('^.*[.-]M\\d+$') || projectVersion.matches('^.*[.-]RC\\d+$')
+	}
+
+	static boolean isRelease(String projectVersion) {
+		return !(isSnapshot(projectVersion) || isMilestone(projectVersion))
 	}
 
 	private static String projectVersion(Project project) {