Fix NoGuavaSetsNewHashSet to skip Iterable-only arguments

Addresses issue #881 where Sets.newHashSet(Iterables.filter(...))
was incorrectly transformed to broken code using Arrays.asList().

The recipe now:
- Only transforms Sets.newHashSet(Collection) to new HashSet<>(Collection)
- Skips transformation for Iterable-only arguments (not Collection)
- Preserves the original Guava code when a safe transformation is not possible

This conservative approach prevents generating code with type inference
failures and compilation errors.

Test cases added:
- setsNewHashSetWithIterablesFilter: Verifies Iterables.filter() is skipped
- setsNewHashSetWithCustomIterable: Verifies custom Iterable is skipped
- setsNewHashSetWithCollectionStillWorks: Verifies Collection case still works

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: timtebeek

src/main/java/org/openrewrite/java/migrate/guava/NoGuavaSetsNewHashSet.java

@@ -55,22 +55,33 @@ public TreeVisitor<?, ExecutionContext> getVisitor() {
             @Override
             public J visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
                 if (NEW_HASH_SET.matches(method)) {
-                    maybeRemoveImport("com.google.common.collect.Sets");
-                    maybeAddImport("java.util.HashSet");
                     if (method.getArguments().isEmpty() || method.getArguments().get(0) instanceof J.Empty) {
+                        maybeRemoveImport("com.google.common.collect.Sets");
+                        maybeAddImport("java.util.HashSet");
                         return JavaTemplate.builder("new HashSet<>()")
                                 .contextSensitive()
                                 .imports("java.util.HashSet")
                                 .build()
                                 .apply(getCursor(), method.getCoordinates().replace());
                     }
-                    if (method.getArguments().size() == 1 && TypeUtils.isAssignableTo("java.util.Collection", method.getArguments().get(0).getType())) {
-                        return JavaTemplate.builder("new HashSet<>(#{any(java.util.Collection)})")
-                                .contextSensitive()
-                                .imports("java.util.HashSet")
-                                .build()
-                                .apply(getCursor(), method.getCoordinates().replace(), method.getArguments().get(0));
+                    if (method.getArguments().size() == 1) {
+                        // Only handle if it's a Collection (not just any Iterable)
+                        if (TypeUtils.isAssignableTo("java.util.Collection", method.getArguments().get(0).getType())) {
+                            maybeRemoveImport("com.google.common.collect.Sets");
+                            maybeAddImport("java.util.HashSet");
+                            return JavaTemplate.builder("new HashSet<>(#{any(java.util.Collection)})")
+                                    .contextSensitive()
+                                    .imports("java.util.HashSet")
+                                    .build()
+                                    .apply(getCursor(), method.getCoordinates().replace(), method.getArguments().get(0));
+                        }
+                        // Skip Iterable-only cases to avoid generating broken code
+                        if (TypeUtils.isAssignableTo("java.lang.Iterable", method.getArguments().get(0).getType())) {
+                            return method;
+                        }
                     }
+                    maybeRemoveImport("com.google.common.collect.Sets");
+                    maybeAddImport("java.util.HashSet");
                     maybeAddImport("java.util.Arrays");
                     JavaTemplate newHashSetVarargs = JavaTemplate.builder("new HashSet<>(Arrays.asList(" + method.getArguments().stream().map(a -> "#{any()}").collect(joining(",")) + "))")
                             .contextSensitive()

src/test/java/org/openrewrite/java/migrate/guava/NoGuavaSetsNewHashSetTest.java

@@ -118,4 +118,83 @@ class Test {
           )
         );
     }
+
+    @Test
+    void setsNewHashSetWithIterablesFilter() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              import java.util.ArrayList;
+              import java.util.List;
+
+              import com.google.common.collect.Iterables;
+              import com.google.common.collect.Sets;
+
+              class Test {
+                  public static void test() {
+                      final List<ClassCastException> result = new ArrayList<ClassCastException>();
+                      List<Exception> myExceptions = new ArrayList<Exception>();
+                      result.addAll(Sets.newHashSet(Iterables.filter(myExceptions, ClassCastException.class)));
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void setsNewHashSetWithCustomIterable() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              import com.google.common.collect.Sets;
+
+              class Test {
+                  public static void test() {
+                      Iterable<String> myIterable = () -> java.util.List.of("a", "b").iterator();
+                      var result = Sets.newHashSet(myIterable);
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @Test
+    void setsNewHashSetWithCollectionStillWorks() {
+        //language=java
+        rewriteRun(
+          java(
+            """
+              import com.google.common.collect.Sets;
+
+              import java.util.ArrayList;
+              import java.util.List;
+              import java.util.Set;
+
+              class Test {
+                  public static void test() {
+                      List<String> myList = new ArrayList<>();
+                      Set<String> result = Sets.newHashSet(myList);
+                  }
+              }
+              """,
+            """
+              import java.util.ArrayList;
+              import java.util.HashSet;
+              import java.util.List;
+              import java.util.Set;
+
+              class Test {
+                  public static void test() {
+                      List<String> myList = new ArrayList<>();
+                      Set<String> result = new HashSet<>(myList);
+                  }
+              }
+              """
+          )
+        );
+    }
 }