Only bump Maven plugin version property when needed

Author: timtebeek

rewrite-maven/src/main/java/org/openrewrite/maven/UpgradePluginVersion.java

@@ -182,8 +182,10 @@ public Xml visitTag(Xml.Tag tag, ExecutionContext ctx) {
                 if (versionTag.isPresent()) {
                     String version = versionTag.get().getValue().orElse(null);
                     if (version != null) {
-                        if (version.trim().startsWith("${") && !newVersion.equals(getResolutionResult().getPom().getValue(version.trim()))) {
-                            doAfterVisit(new ChangePropertyValue(version, newVersion, false, false).getVisitor());
+                        if (version.trim().startsWith("${")) {
+                            if (!newVersion.equals(getResolutionResult().getPom().getValue(version.trim()))) {
+                                doAfterVisit(new ChangePropertyValue(version, newVersion, false, false).getVisitor());
+                            }
                         } else if (!newVersion.equals(version)) {
                             doAfterVisit(new ChangeTagValueVisitor<>(versionTag.get(), newVersion));
                         }