Improve static error message.

src/main/kotlin/Submission.kt

@@ -500,7 +500,8 @@ class SubmissionDesignExtraFieldError(klass: Class<*>, field: Field) : Submissio
 )
 
 class SubmissionStaticFieldError(klass: Class<*>, field: Field) : SubmissionDesignError(
-    "Field ${field.fullName()} is static in submission class ${klass.name} but no current support for static fields"
+    "Field ${field.fullName()} is static in submission class ${klass.name}, " +
+        "but static fields are not used by the solution"
 )
 
 class SubmissionDesignClassError(klass: Class<*>, message: String) : SubmissionDesignError(

src/main/resources/edu.illinois.cs.cs125.jenisol.core.version

@@ -1 +1 @@
-version=2021.6.7
+version=2021.6.8

src/test/java/edu/illinois/cs/cs125/jenisol/core/TestJavaExamples.kt

@@ -295,6 +295,9 @@ class TestJavaExamples : StringSpec(
         examples.java.noreceiver.arrayreturn.Correct::class.java.also {
             "${it.testName()}" { it.test() }
         }
+        examples.java.receiver.rejectstaticfield.Correct::class.java.also {
+            "${it.testName()}" { it.test() }
+        }
         examples.java.receiver.timeouttest.Correct::class.java.also {
             "${it.testName()}" {
                 val runnable = object : Runnable {

src/test/java/examples/java/receiver/rejectstaticfield/Correct.java

@@ -0,0 +1,9 @@
+package examples.java.receiver.rejectstaticfield;
+
+public class Correct {
+  private int i = 0;
+
+  public int increment() {
+    return i++;
+  }
+}

src/test/java/examples/java/receiver/rejectstaticfield/Design0.java

@@ -0,0 +1,9 @@
+package examples.java.receiver.rejectstaticfield;
+
+public class Design0 {
+  private static int i = 0;
+
+  public int increment() {
+    return i++;
+  }
+}

src/test/java/examples/java/receiver/rejectstaticfield/Incorrect0.java

@@ -0,0 +1,9 @@
+package examples.java.receiver.rejectstaticfield;
+
+public class Incorrect0 {
+  private int i = 0;
+
+  public int increment() {
+    return ++i;
+  }
+}