import: ensure imported classes are not lost after on demand folding (IDEA-132190)

java/java-impl/src/com/intellij/psi/impl/source/codeStyle/ImportHelper.java

@@ -362,7 +362,11 @@ public class ImportHelper{
    * Adds import if it is needed.
    * @return false when the FQ-name have to be used in code (e.g. when conflicting imports already exist)
    */
-  public boolean addImport(@NotNull PsiJavaFile file, @NotNull PsiClass refClass){
+  public boolean addImport(@NotNull PsiJavaFile file, @NotNull PsiClass refClass) {
+    return addImport(file, refClass, false);
+  }
+
+  private boolean addImport(@NotNull PsiJavaFile file, @NotNull PsiClass refClass, boolean forceReimport){
     final JavaPsiFacade facade = JavaPsiFacade.getInstance(file.getProject());
     PsiElementFactory factory = facade.getElementFactory();
     PsiResolveHelper helper = facade.getResolveHelper();
@@ -377,7 +381,7 @@ public class ImportHelper{
     String shortName = PsiNameHelper.getShortClassName(className);
 
     PsiClass conflictSingleRef = findSingleImportByShortName(file, shortName);
-    if (conflictSingleRef != null){
+    if (conflictSingleRef != null && !forceReimport){
       return className.equals(conflictSingleRef.getQualifiedName());
     }
 
@@ -449,7 +453,7 @@ public class ImportHelper{
 
       for (PsiClass aClass : classesToReimport) {
         if (aClass != null) {
-          addImport(file, aClass);
+          addImport(file, aClass, true);
         }
       }
     }

java/java-tests/testSrc/com/intellij/codeInsight/intention/AddImportActionTest.groovy

@@ -115,6 +115,58 @@ public class Foo extends goo.Super {
 '''
   }
 
+  public void testImportFoldingWithConflicts() {
+
+    myFixture.addClass 'package p1; public class B {}'
+    myFixture.addClass 'package p1; public class A1 {}'
+    myFixture.addClass 'package p1; public class A2 {}'
+    myFixture.addClass 'package p1; public class A3 {}'
+    myFixture.addClass 'package p1; public class A4 {}'
+    myFixture.addClass 'package p1; public class A5 {}'
+
+    myFixture.addClass 'package p2; public class B {}'
+    myFixture.configureByText 'C.java', '''package p2;
+
+import p1.A1;
+import p1.A2;
+import p1.A3;
+import p1.A4;
+import p1.B;
+
+class C {
+
+     A1 a1;
+     A2 a2;
+     A3 a3;
+     A4 a4;
+     A<caret>5 a5;
+
+     B b;
+}
+
+'''
+    importClass()
+
+    myFixture.checkResult '''package p2;
+
+import p1.*;
+import p1.B;
+
+class C {
+
+     A1 a1;
+     A2 a2;
+     A3 a3;
+     A4 a4;
+     A5 a5;
+
+     B b;
+}
+
+'''
+  }
+
+
   public void testAnnotatedImport() {
     myFixture.configureByText 'a.java', '''
 import java.lang.annotation.*;