consider user property ratchetFrom to have priority over formatter config

closes #2842

Author: mkhl

plugin-maven/src/main/java/com/diffplug/spotless/maven/AbstractSpotlessMojo.java

@@ -39,6 +39,7 @@
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
+import org.apache.maven.execution.MavenSession;
 import org.apache.maven.plugin.AbstractMojo;
 import org.apache.maven.plugin.MojoExecutionException;
 import org.apache.maven.plugins.annotations.Component;
@@ -107,6 +108,9 @@ public abstract class AbstractSpotlessMojo extends AbstractMojo {
 	@Component
 	protected BuildContext buildContext;
 
+	@Component
+	private MavenSession mavenSession;
+
 	@Parameter(defaultValue = "${mojoExecution.goal}", required = true, readonly = true)
 	private String goal;
 
@@ -401,9 +405,10 @@ private FormatterConfig getFormatterConfig() {
 		P2Provisioner p2Provisioner = P2Provisioner.createDefault();
 		List<FormatterStepFactory> formatterStepFactories = getFormatterStepFactories();
 		FileLocator fileLocator = getFileLocator();
+		final Optional<String> userRatchetFrom = Optional.ofNullable((String) mavenSession.getUserProperties().get("ratchetFrom"));
 		final Optional<String> optionalRatchetFrom = Optional.ofNullable(this.ratchetFrom)
 				.filter(ratchet -> !RATCHETFROM_NONE.equals(ratchet));
-		return new FormatterConfig(baseDir, encoding, lineEndings, optionalRatchetFrom, provisioner, p2Provisioner, fileLocator, formatterStepFactories, Optional.ofNullable(setLicenseHeaderYearsFromGitHistory), lintSuppressions);
+		return new FormatterConfig(baseDir, encoding, lineEndings, userRatchetFrom, optionalRatchetFrom, provisioner, p2Provisioner, fileLocator, formatterStepFactories, Optional.ofNullable(setLicenseHeaderYearsFromGitHistory), lintSuppressions);
 	}
 
 	private FileLocator getFileLocator() {

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterConfig.java

@@ -30,6 +30,7 @@ public class FormatterConfig {
 
 	private final String encoding;
 	private final LineEnding lineEndings;
+	private final Optional<String> userRatchetFrom;
 	private final Optional<String> ratchetFrom;
 	private final Provisioner provisioner;
 	private final P2Provisioner p2Provisioner;
@@ -38,10 +39,11 @@ public class FormatterConfig {
 	private final Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory;
 	private final List<LintSuppression> lintSuppressions;
 
-	public FormatterConfig(File baseDir, String encoding, LineEnding lineEndings, Optional<String> ratchetFrom, Provisioner provisioner,
+	public FormatterConfig(File baseDir, String encoding, LineEnding lineEndings, Optional<String> userRatchetFrom, Optional<String> ratchetFrom, Provisioner provisioner,
 			P2Provisioner p2Provisioner, FileLocator fileLocator, List<FormatterStepFactory> globalStepFactories, Optional<String> spotlessSetLicenseHeaderYearsFromGitHistory, List<LintSuppression> lintSuppressions) {
 		this.encoding = encoding;
 		this.lineEndings = lineEndings;
+		this.userRatchetFrom = userRatchetFrom;
 		this.ratchetFrom = ratchetFrom;
 		this.provisioner = provisioner;
 		this.p2Provisioner = p2Provisioner;
@@ -59,6 +61,10 @@ public LineEnding getLineEndings() {
 		return lineEndings;
 	}
 
+	public Optional<String> getUserRatchetFrom() {
+		return userRatchetFrom;
+	}
+
 	public Optional<String> getRatchetFrom() {
 		return ratchetFrom;
 	}

plugin-maven/src/main/java/com/diffplug/spotless/maven/FormatterFactory.java

@@ -175,13 +175,15 @@ private LineEnding lineEndings(FormatterConfig config) {
 	}
 
 	Optional<String> ratchetFrom(FormatterConfig config) {
-		if (RATCHETFROM_NOT_SET_AT_FORMAT_LEVEL.equals(ratchetFrom)) {
-			return config.getRatchetFrom();
-		} else if (RATCHETFROM_NONE.equals(ratchetFrom)) {
-			return Optional.empty();
-		} else {
-			return Optional.ofNullable(ratchetFrom);
-		}
+		return config.getUserRatchetFrom()
+				.or(this::optionalRatchetFrom)
+				.or(config::getRatchetFrom)
+				.filter(ratchet -> !RATCHETFROM_NONE.equals(ratchet));
+	}
+
+	private Optional<String> optionalRatchetFrom() {
+		return Optional.ofNullable(ratchetFrom)
+				.filter(ratchet -> !RATCHETFROM_NOT_SET_AT_FORMAT_LEVEL.equals(ratchet));
 	}
 
 	private FormatterStepConfig stepConfig(Charset encoding, FormatterConfig config) {