Remove unused imports in MigrateCollectionsSingletonList

Author: timtebeek

src/main/java/org/openrewrite/java/migrate/util/MigrateCollectionsSingletonList.java

@@ -15,14 +15,12 @@
  */
 package org.openrewrite.java.migrate.util;
 
-import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
 import org.openrewrite.java.JavaIsoVisitor;
 import org.openrewrite.java.MethodMatcher;
 import org.openrewrite.java.NoMissingTypes;
 import org.openrewrite.java.search.UsesJavaVersion;
 import org.openrewrite.java.search.UsesMethod;
-import org.openrewrite.java.tree.Expression;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.JavaType;
 import org.openrewrite.java.tree.JavaType.ShallowClass;