Limit RemoveSystemOutPrintln to System.out and System.err (#770)

Author: timtebeek

src/main/java/org/openrewrite/staticanalysis/RemoveSystemOutPrintln.java

@@ -26,6 +26,7 @@
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.JRightPadded;
 import org.openrewrite.java.tree.Space;
+import org.openrewrite.java.tree.TypeUtils;
 import org.openrewrite.marker.Markers;
 
 import static java.util.Collections.emptyList;
@@ -41,7 +42,8 @@ public String getDisplayName() {
 
     @Override
     public String getDescription() {
-        return "Print statements are often left accidentally after debugging an issue.";
+        return "Print statements are often left accidentally after debugging an issue. " +
+                "This recipe removes all `System.out#println` and `System.err#println` statements from the code.";
     }
 
     @Override
@@ -60,8 +62,11 @@ public J.Lambda visitLambda(J.Lambda lambda, ExecutionContext ctx) {
 
             @Override
             @SuppressWarnings("NullableProblems")
-            public  J.@Nullable MethodInvocation visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
-                if (SYSTEM_OUT_PRINTLN.matches(method)) {
+            public J.@Nullable MethodInvocation visitMethodInvocation(J.MethodInvocation method, ExecutionContext ctx) {
+                if (SYSTEM_OUT_PRINTLN.matches(method) &&
+                        method.getSelect() instanceof J.FieldAccess &&
+                        (((J.FieldAccess) method.getSelect()).getTarget() instanceof J.Identifier &&
+                                TypeUtils.isAssignableTo("java.lang.System", ((J.FieldAccess) method.getSelect()).getTarget().getType()))) {
                     return null;
                 }
                 return super.visitMethodInvocation(method, ctx);

src/test/java/org/openrewrite/staticanalysis/RemoveSystemOutPrintlnTest.java

@@ -36,15 +36,30 @@ void removePrintln() {
           //language=java
           java(
             """
+              import java.io.PrintStream;
+
               class Test {
-                  void test() {
+                  void printOut() {
                       System.out.println("Hello, world!");
                   }
+                  void printErr() {
+                      System.err.println("Hello, world!");
+                  }
+                  void printStream(PrintStream printStream) {
+                      printStream.println("Hello, world!");
+                  }
               }
               """,
             """
+              import java.io.PrintStream;
+
               class Test {
-                  void test() {
+                  void printOut() {
+                  }
+                  void printErr() {
+                  }
+                  void printStream(PrintStream printStream) {
+                      printStream.println("Hello, world!");
                   }
               }
               """