UpdateSdkMan recipe should not allow a downgrade of Java version (#771)

* Adding test for UpdateSdkMan showing where it incorrectly downgrades the version if high enough already

* Guarding against the new version being lower than the current version for `UpdateSdkMan`

* Tweaking logic a bit to allow for specifying just the major version and a different distribution and still allowing it to switch distributions if it can find a higher version number than the current one.

* Adding additional test cases to show it is still working for specific scenarios of providng a more generic version number that still scopes the current version number

Author: steve-aom-elliott

src/main/java/org/openrewrite/java/migrate/UpdateSdkMan.java

@@ -102,13 +102,17 @@ public Tree visit(@Nullable Tree tree, ExecutionContext ctx) {
                             .filter(candidate -> releaseComparator.isValid(newBasis, candidate))
                             .max(releaseComparator)
                             .orElse(null);
-                    if (idealCandidate != null) {
+                    if (idealCandidate != null && !isRequestedDowngrade(matcher.group(1) + dist, idealCandidate, dist)) {
                         return plainText.withText(matcher.replaceFirst("java=" + idealCandidate));
                     }
                 }
                 return sourceFile;
             }
 
+            private boolean isRequestedDowngrade(String currentVersionWithNewDist, String requestedVersionWithDist, String dist) {
+                return new LatestRelease(dist).compare(null, currentVersionWithNewDist, requestedVersionWithDist) > 0;
+            }
+
             private List<String> readSdkmanJavaCandidates() {
                 try (InputStream resourceAsStream = UpdateSdkMan.class.getResourceAsStream("/sdkman-java.csv");
                      InputStreamReader inputStreamReader = new InputStreamReader(resourceAsStream, StandardCharsets.UTF_8);

src/test/java/org/openrewrite/java/migrate/UpdateSdkManTest.java

@@ -166,4 +166,62 @@ void zuluNonCrac() {
           )
         );
     }
+
+    @Test
+    void upgradeIfNewVersionIsStillSameVersionBasisAndSameDistribution() {
+        rewriteRun(
+          spec -> spec.recipe(new UpdateSdkMan("21", null)),
+          text(
+            """
+              java=21.0.6-zulu
+              """,
+            """
+              java=21.0.7-zulu
+              """,
+            spec -> spec.path(".sdkmanrc")
+          )
+        );
+    }
+
+    @Test
+    void upgradeIfNewVersionIsStillSameVersionBasisAndDifferentDistribution() {
+        rewriteRun(
+          spec -> spec.recipe(new UpdateSdkMan("23", "amzn")),
+          text(
+            """
+              java=23.0.1-open
+              """,
+            """
+              java=23.0.2-amzn
+              """,
+            spec -> spec.path(".sdkmanrc")
+          )
+        );
+    }
+
+    @Test
+    void doNotDowngradeVersionIfAlreadyHighEnoughSameDistribution() {
+        rewriteRun(
+          spec -> spec.recipe(new UpdateSdkMan("17", null)),
+          text(
+            """
+              java=24-librca
+              """,
+            spec -> spec.path(".sdkmanrc")
+          )
+        );
+    }
+
+    @Test
+    void doNotDowngradeVersionIfAlreadyHighEnoughDifferentDistribution() {
+        rewriteRun(
+          spec -> spec.recipe(new UpdateSdkMan("23", "zulu")),
+          text(
+            """
+              java=24-amzn
+              """,
+            spec -> spec.path(".sdkmanrc")
+          )
+        );
+    }
 }