type migration: add a test for IDEA-173791

java/typeMigration/testData/intentions/threadLocal/afterCycle.java

@@ -0,0 +1,8 @@
+// "Convert to ThreadLocal" "true"
+import java.util.Arrays;
+
+class Foo {
+    private final ThreadLocal<char[]> lookahead = ThreadLocal.withInitial(() -> new char[0]);
+
+  { lookahead.set(Arrays.copyOf(lookahead.get(), 42));}
+}

java/typeMigration/testData/intentions/threadLocal/beforeCycle.java

@@ -0,0 +1,8 @@
+// "Convert to ThreadLocal" "true"
+import java.util.Arrays;
+
+class Foo {
+  private char[] loo<caret>kahead = new char[0];
+
+  { lookahead = Arrays.copyOf(lookahead, 42);}
+}