introduce injected fragment as string (IDEA-90322)

java/java-tests/testData/refactoring/introduceVariable/FromInjected.after.java

@@ -0,0 +1,6 @@
+class Test {
+  {
+      String regexp = "|\t";
+      String[] parts = "".split(regexp);
+  }
+}

java/java-tests/testData/refactoring/introduceVariable/FromInjected.java

@@ -0,0 +1,5 @@
+class Test {
+  {
+    String[] parts = "".split("|<caret>\t");
+  }
+}