set an import order for Java code

build.gradle

@@ -399,10 +399,15 @@ subprojects {
             // allows us to use spotless:off / spotless:on to keep pre-formatted sections
             toggleOffOn()
 
+            removeUnusedImports()
             eclipse().configFile("$rootDir/scripts/tools/checkstyle/keyCodeStyle.xml")
             trimTrailingWhitespace()        // not sure how to set this in the xml file ...
             //googleJavaFormat().aosp().reflowLongStrings()
 
+            // note: you can use an empty string for all the imports you didn't specify explicitly,
+            // '|' to join group without blank line, and '\\#` prefix for static imports
+            importOrder('java|javax', 'de.uka', 'org.key_project', '', '\\#')
+
             // specific delimiter: normally just 'package', but spotless crashes for files in default package
             // (see https://github.com/diffplug/spotless/issues/30), therefore 'import' is needed. '//' is for files
             // with completely commented out code (which would probably better just be removed in future).

key.core.example/src/main/java/org/key_project/Main.java

@@ -6,8 +6,6 @@
 import java.util.List;
 import java.util.Set;
 
-import org.key_project.util.collection.ImmutableSet;
-
 import de.uka.ilkd.key.control.KeYEnvironment;
 import de.uka.ilkd.key.java.abstraction.KeYJavaType;
 import de.uka.ilkd.key.logic.op.IObserverFunction;
@@ -20,6 +18,9 @@
 import de.uka.ilkd.key.strategy.StrategyProperties;
 import de.uka.ilkd.key.util.KeYTypeUtil;
 import de.uka.ilkd.key.util.MiscTools;
+
+import org.key_project.util.collection.ImmutableSet;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 

key.core.proof_references/src/main/java/de/uka/ilkd/key/proof_references/ProofReferenceUtil.java

@@ -1,17 +1,18 @@
 package de.uka.ilkd.key.proof_references;
 
+import java.util.LinkedHashSet;
+
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.proof.Node;
 import de.uka.ilkd.key.proof.Proof;
 import de.uka.ilkd.key.proof.ProofVisitor;
 import de.uka.ilkd.key.proof_references.analyst.*;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
+
 import org.key_project.util.collection.ImmutableList;
 import org.key_project.util.collection.ImmutableSLList;
 import org.key_project.util.java.CollectionUtil;
 
-import java.util.LinkedHashSet;
-
 /**
  * <p>
  * This class provides static methods to compute proof references. A proof reference is a source

key.core.proof_references/src/main/java/de/uka/ilkd/key/proof_references/analyst/ClassAxiomAndInvariantProofReferencesAnalyst.java

@@ -3,9 +3,6 @@
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 
-import org.key_project.util.collection.DefaultImmutableSet;
-import org.key_project.util.collection.ImmutableSet;
-
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.java.abstraction.KeYJavaType;
 import de.uka.ilkd.key.logic.Name;
@@ -23,6 +20,9 @@
 import de.uka.ilkd.key.util.MiscTools;
 import de.uka.ilkd.key.util.Pair;
 
+import org.key_project.util.collection.DefaultImmutableSet;
+import org.key_project.util.collection.ImmutableSet;
+
 /**
  * Extracts used {@link ClassAxiom} and {@link ClassInvariant}s.
  *

key.core.proof_references/src/main/java/de/uka/ilkd/key/proof_references/analyst/MethodCallProofReferencesAnalyst.java

@@ -2,9 +2,6 @@
 
 import java.util.LinkedHashSet;
 
-import org.key_project.util.collection.ImmutableArray;
-import org.key_project.util.collection.ImmutableSLList;
-
 import de.uka.ilkd.key.java.JavaTools;
 import de.uka.ilkd.key.java.ProgramElement;
 import de.uka.ilkd.key.java.Services;
@@ -30,6 +27,9 @@
 import de.uka.ilkd.key.rule.RuleApp;
 import de.uka.ilkd.key.util.MiscTools;
 
+import org.key_project.util.collection.ImmutableArray;
+import org.key_project.util.collection.ImmutableSLList;
+
 /**
  * Extracts called methods.
  *

key.core.proof_references/src/main/java/de/uka/ilkd/key/proof_references/reference/DefaultProofReference.java

@@ -1,12 +1,12 @@
 package de.uka.ilkd.key.proof_references.reference;
 
-import de.uka.ilkd.key.proof.Node;
-import de.uka.ilkd.key.proof.Proof;
-
 import java.util.Collection;
 import java.util.LinkedHashSet;
 import java.util.Objects;
 
+import de.uka.ilkd.key.proof.Node;
+import de.uka.ilkd.key.proof.Proof;
+
 /**
  * Default implementation of {@link IProofReference}.
  *

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/AbstractProofReferenceTestCase.java

@@ -1,5 +1,11 @@
 package de.uka.ilkd.key.proof_references.testcase;
 
+import java.io.File;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashSet;
+import java.util.function.Predicate;
+
 import de.uka.ilkd.key.control.KeYEnvironment;
 import de.uka.ilkd.key.java.abstraction.KeYJavaType;
 import de.uka.ilkd.key.logic.Choice;
@@ -18,19 +24,14 @@
 import de.uka.ilkd.key.speclang.FunctionalOperationContract;
 import de.uka.ilkd.key.strategy.StrategyProperties;
 import de.uka.ilkd.key.util.HelperClassForTests;
+
 import org.key_project.util.collection.DefaultImmutableSet;
 import org.key_project.util.collection.ImmutableList;
 import org.key_project.util.collection.ImmutableSLList;
 import org.key_project.util.collection.ImmutableSet;
 import org.key_project.util.helper.FindResources;
 import org.key_project.util.java.CollectionUtil;
 
-import java.io.File;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.LinkedHashSet;
-import java.util.function.Predicate;
-
 import static org.junit.jupiter.api.Assertions.*;
 
 /**

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/TestKeYTypeUtil.java

@@ -6,6 +6,7 @@
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.java.abstraction.KeYJavaType;
 import de.uka.ilkd.key.util.KeYTypeUtil;
+
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/TestProofReferenceUtil.java

@@ -1,18 +1,20 @@
 package de.uka.ilkd.key.proof_references.testcase;
 
+import java.io.File;
+import java.util.LinkedHashSet;
+
 import de.uka.ilkd.key.proof.Node;
 import de.uka.ilkd.key.proof.Proof;
 import de.uka.ilkd.key.proof_references.ProofReferenceUtil;
 import de.uka.ilkd.key.proof_references.analyst.ContractProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.analyst.IProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.analyst.MethodBodyExpandProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
-import org.junit.jupiter.api.Test;
+
 import org.key_project.util.collection.ImmutableList;
 import org.key_project.util.collection.ImmutableSLList;
 
-import java.io.File;
-import java.util.LinkedHashSet;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests for {@link ProofReferenceUtil}.

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/analyst/TestClassAxiomAndInvariantProofReferencesAnalyst.java

@@ -3,6 +3,7 @@
 import de.uka.ilkd.key.proof_references.analyst.ClassAxiomAndInvariantProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
 import de.uka.ilkd.key.proof_references.testcase.AbstractProofReferenceTestCase;
+
 import org.junit.jupiter.api.Test;
 
 /**

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/analyst/TestContractProofReferencesAnalyst.java

@@ -3,6 +3,7 @@
 import de.uka.ilkd.key.proof_references.analyst.ContractProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
 import de.uka.ilkd.key.proof_references.testcase.AbstractProofReferenceTestCase;
+
 import org.junit.jupiter.api.Test;
 
 /**

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/analyst/TestMethodBodyExpandProofReferencesAnalyst.java

@@ -3,6 +3,7 @@
 import de.uka.ilkd.key.proof_references.analyst.MethodBodyExpandProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
 import de.uka.ilkd.key.proof_references.testcase.AbstractProofReferenceTestCase;
+
 import org.junit.jupiter.api.Test;
 
 /**

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/analyst/TestMethodCallProofReferencesAnalyst.java

@@ -3,6 +3,7 @@
 import de.uka.ilkd.key.proof_references.analyst.MethodCallProofReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
 import de.uka.ilkd.key.proof_references.testcase.AbstractProofReferenceTestCase;
+
 import org.junit.jupiter.api.Test;
 
 /**

key.core.proof_references/src/test/java/de/uka/ilkd/key/proof_references/testcase/analyst/TestProgramVariableReferencesAnalyst.java

@@ -3,6 +3,7 @@
 import de.uka.ilkd.key.proof_references.analyst.ProgramVariableReferencesAnalyst;
 import de.uka.ilkd.key.proof_references.reference.IProofReference;
 import de.uka.ilkd.key.proof_references.testcase.AbstractProofReferenceTestCase;
+
 import org.junit.jupiter.api.Test;
 
 /**

key.core.symbolic_execution.example/src/main/java/org/key_project/example/Main.java

@@ -4,9 +4,6 @@
 import java.util.HashMap;
 import java.util.List;
 
-import org.key_project.util.collection.ImmutableSLList;
-import org.key_project.util.java.StringUtil;
-
 import de.uka.ilkd.key.control.DefaultUserInterfaceControl;
 import de.uka.ilkd.key.control.KeYEnvironment;
 import de.uka.ilkd.key.java.abstraction.KeYJavaType;
@@ -29,6 +26,10 @@
 import de.uka.ilkd.key.symbolic_execution.util.SymbolicExecutionEnvironment;
 import de.uka.ilkd.key.symbolic_execution.util.SymbolicExecutionUtil;
 import de.uka.ilkd.key.util.MiscTools;
+
+import org.key_project.util.collection.ImmutableSLList;
+import org.key_project.util.java.StringUtil;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/BlockContractValidityTermLabelUpdate.java

@@ -1,5 +1,7 @@
 package de.uka.ilkd.key.rule.label;
 
+import java.util.Set;
+
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.logic.JavaBlock;
 import de.uka.ilkd.key.logic.Name;
@@ -15,13 +17,12 @@
 import de.uka.ilkd.key.rule.Rule;
 import de.uka.ilkd.key.rule.RuleApp;
 import de.uka.ilkd.key.symbolic_execution.util.SymbolicExecutionUtil;
+
 import org.key_project.util.collection.ImmutableArray;
 import org.key_project.util.collection.ImmutableList;
 import org.key_project.util.collection.ImmutableSLList;
 import org.key_project.util.java.CollectionUtil;
 
-import java.util.Set;
-
 /**
  * Makes sure that {@link BlockContractValidityTermLabel} is introduced when a
  * {@link BlockContractInternalRule} is applied.

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/FormulaTermLabelMerger.java

@@ -2,11 +2,8 @@
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.LinkedList;
 import java.util.List;
 
-import org.key_project.util.java.CollectionUtil;
-
 import de.uka.ilkd.key.logic.SequentFormula;
 import de.uka.ilkd.key.logic.Term;
 import de.uka.ilkd.key.logic.label.FormulaTermLabel;

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/FormulaTermLabelRefactoring.java

@@ -1,5 +1,7 @@
 package de.uka.ilkd.key.rule.label;
 
+import java.util.*;
+
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.logic.*;
 import de.uka.ilkd.key.logic.label.FormulaTermLabel;
@@ -11,11 +13,10 @@
 import de.uka.ilkd.key.rule.SyntacticalReplaceVisitor;
 import de.uka.ilkd.key.rule.merge.CloseAfterMerge;
 import de.uka.ilkd.key.symbolic_execution.TruthValueTracingUtil;
+
 import org.key_project.util.collection.ImmutableList;
 import org.key_project.util.java.CollectionUtil;
 
-import java.util.*;
-
 /**
  * The {@link TermLabelRefactoring} used to label predicates with a {@link FormulaTermLabel} on
  * applied loop invariants or operation contracts.

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/FormulaTermLabelUpdate.java

@@ -1,5 +1,11 @@
 package de.uka.ilkd.key.rule.label;
 
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.logic.*;
 import de.uka.ilkd.key.logic.label.FormulaTermLabel;
@@ -15,16 +21,11 @@
 import de.uka.ilkd.key.rule.Taclet.TacletLabelHint.TacletOperation;
 import de.uka.ilkd.key.rule.TacletApp;
 import de.uka.ilkd.key.symbolic_execution.TruthValueTracingUtil;
+
 import org.key_project.util.collection.ImmutableArray;
 import org.key_project.util.collection.ImmutableList;
 import org.key_project.util.java.CollectionUtil;
 
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.Set;
-
 /**
  * The {@link TermLabelUpdate} used to label predicates with a {@link FormulaTermLabel} of add
  * clauses which were not labeled before.

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/LoopBodyTermLabelUpdate.java

@@ -2,10 +2,6 @@
 
 import java.util.Set;
 
-import org.key_project.util.collection.ImmutableArray;
-import org.key_project.util.collection.ImmutableList;
-import org.key_project.util.collection.ImmutableSLList;
-
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.logic.JavaBlock;
 import de.uka.ilkd.key.logic.Name;
@@ -20,6 +16,10 @@
 import de.uka.ilkd.key.rule.WhileInvariantRule;
 import de.uka.ilkd.key.symbolic_execution.util.SymbolicExecutionUtil;
 
+import org.key_project.util.collection.ImmutableArray;
+import org.key_project.util.collection.ImmutableList;
+import org.key_project.util.collection.ImmutableSLList;
+
 /**
  * Makes sure that {@link SymbolicExecutionUtil#LOOP_BODY_LABEL} is introduced when a
  * {@link WhileInvariantRule} is applied.

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/LoopInvariantNormalBehaviorTermLabelUpdate.java

@@ -2,10 +2,6 @@
 
 import java.util.Set;
 
-import org.key_project.util.collection.ImmutableArray;
-import org.key_project.util.collection.ImmutableList;
-import org.key_project.util.collection.ImmutableSLList;
-
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.logic.JavaBlock;
 import de.uka.ilkd.key.logic.Name;
@@ -20,6 +16,10 @@
 import de.uka.ilkd.key.rule.WhileInvariantRule;
 import de.uka.ilkd.key.symbolic_execution.util.SymbolicExecutionUtil;
 
+import org.key_project.util.collection.ImmutableArray;
+import org.key_project.util.collection.ImmutableList;
+import org.key_project.util.collection.ImmutableSLList;
+
 /**
  * Makes sure that {@link SymbolicExecutionUtil#LOOP_INVARIANT_NORMAL_BEHAVIOR_LABEL} is introduced
  * when a {@link WhileInvariantRule} is applied.

key.core.symbolic_execution/src/main/java/de/uka/ilkd/key/rule/label/RemoveInCheckBranchesTermLabelRefactoring.java

@@ -3,9 +3,6 @@
 import java.util.Iterator;
 import java.util.List;
 
-import org.key_project.util.collection.ImmutableList;
-import org.key_project.util.collection.ImmutableSLList;
-
 import de.uka.ilkd.key.java.Services;
 import de.uka.ilkd.key.logic.Name;
 import de.uka.ilkd.key.logic.PosInOccurrence;
@@ -22,6 +19,9 @@
 import de.uka.ilkd.key.rule.UseOperationContractRule;
 import de.uka.ilkd.key.rule.WhileInvariantRule;
 
+import org.key_project.util.collection.ImmutableList;
+import org.key_project.util.collection.ImmutableSLList;
+
 /**
  * This {@link TermLabelRefactoring} removes the supported {@link TermLabel} in check branches.
  * These are: