Preserve Base64 imports and receiver evaluation

src/test/java/org/openrewrite/java/migrate/UseJavaUtilBase64Test.java

@@ -16,6 +16,7 @@
 package org.openrewrite.java.migrate;
 
 import org.junit.jupiter.api.Test;
+import org.junitpioneer.jupiter.ExpectedToFail;
 import org.openrewrite.DocumentExample;
 import org.openrewrite.Issue;
 import org.openrewrite.java.JavaParser;
@@ -218,6 +219,74 @@ void test(byte[] bBytes) {
         );
     }
 
+    @ExpectedToFail("Import for java.util.Base64 is only added when ChangeType retypes a coder variable; without one the migrated file does not compile")
+    @Test
+    void addImportWhenNoCoderVariablePresent() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              package test.sun.misc;
+
+              class Test {
+                  String test(byte[] bBytes) {
+                      return new BASE64Encoder().encode(bBytes);
+                  }
+              }
+              """,
+            """
+              package test.sun.misc;
+
+              import java.util.Base64;
+
+              class Test {
+                  String test(byte[] bBytes) {
+                      return Base64.getEncoder().encodeToString(bBytes);
+                  }
+              }
+              """
+          )
+        );
+    }
+
+    @ExpectedToFail("Receivers are only put back when they are identifiers; a method call receiver and its side effects are silently dropped")
+    @Test
+    void retainMethodCallReceiver() {
+        rewriteRun(
+          //language=java
+          java(
+            """
+              package test.sun.misc;
+
+              class Test {
+                  BASE64Encoder encoder() {
+                      return new BASE64Encoder();
+                  }
+
+                  String test(byte[] bBytes) {
+                      return encoder().encode(bBytes);
+                  }
+              }
+              """,
+            """
+              package test.sun.misc;
+
+              import java.util.Base64;
+
+              class Test {
+                  Base64.Encoder encoder() {
+                      return Base64.getEncoder();
+                  }
+
+                  String test(byte[] bBytes) {
+                      return encoder().encodeToString(bBytes);
+                  }
+              }
+              """
+          )
+        );
+    }
+
     @Issue("https://github.com/openrewrite/rewrite-migrate-java/issues/212")
     @Test
     void otherBase64() {