Use spotless to enforce/verify formatting conventions (#2985)

to reduce potential discussion surface

Author: pivovarit

pom.xml

@@ -75,6 +75,7 @@ We use these goals frequently to keep the dependencies and plugins up-to-date:
         <maven.release.version>3.1.1</maven.release.version>
         <maven.versions.version>2.18.0</maven.versions.version>
         <maven.surefire.version>3.5.2</maven.surefire.version>
+        <spotless.version>2.44.2</spotless.version>
         <maven.source.version>3.3.1</maven.source.version>
         <maven.exec.version>3.5.0</maven.exec.version>
         <moditect.version>1.2.2.Final</moditect.version>
@@ -437,6 +438,41 @@ We use these goals frequently to keep the dependencies and plugins up-to-date:
             </build>
         </profile>
 
+        <profile>
+            <id>spotless</id>
+            <activation>
+                <jdk>[11,)</jdk>
+            </activation>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>com.diffplug.spotless</groupId>
+                        <artifactId>spotless-maven-plugin</artifactId>
+                        <version>${spotless.version}</version>
+                        <configuration>
+                            <java>
+                                <removeUnusedImports/>
+                                <importOrder>
+                                    <order>,\#</order>
+                                </importOrder>
+                                <endWithNewline/>
+                            </java>
+                        </configuration>
+                        <executions>
+                            <execution>
+                                <goals>
+                                    <goal>check</goal>
+                                </goals>
+                                <phase>compile</phase>
+                            </execution>
+                        </executions>
+                    </plugin>
+
+                </plugins>
+            </build>
+        </profile>
+
+
         <!-- A profile for eliminating eclipse m2e warnings -->
         <profile>
             <id>eclipse-m2e</id>

vavr/src/main/java/io/vavr/$.java

@@ -18,14 +18,14 @@
  */
 package io.vavr;
 
+import io.vavr.collection.List;
+import io.vavr.concurrent.Future;
 import io.vavr.control.Either;
+import io.vavr.control.Option;
 import io.vavr.control.Try;
 import io.vavr.control.Validation;
 import io.vavr.match.annotation.Patterns;
 import io.vavr.match.annotation.Unapply;
-import io.vavr.collection.List;
-import io.vavr.concurrent.Future;
-import io.vavr.control.Option;
 
 /**
  * <strong>INTERNAL TYPE - turned to io.vavr.Patterns by vavr-match annotation processor.</strong>

vavr/src/main/java/io/vavr/Lazy.java

@@ -22,7 +22,6 @@
 import io.vavr.collection.Seq;
 import io.vavr.collection.Vector;
 import io.vavr.control.Option;
-
 import java.io.IOException;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;

vavr/src/main/java/io/vavr/PartialFunction.java

@@ -19,7 +19,6 @@
 package io.vavr;
 
 import io.vavr.control.Option;
-
 import java.util.function.Function;
 
 /**

vavr/src/main/java/io/vavr/Predicates.java

@@ -20,7 +20,6 @@
 
 import io.vavr.collection.Iterator;
 import io.vavr.collection.List;
-
 import java.util.Objects;
 import java.util.function.Predicate;
 

vavr/src/main/java/io/vavr/Value.java

@@ -18,6 +18,7 @@
  */
 package io.vavr;
 
+import io.vavr.collection.*;
 import io.vavr.collection.Array;
 import io.vavr.collection.CharSeq;
 import io.vavr.collection.HashMap;
@@ -27,7 +28,6 @@
 import io.vavr.collection.LinkedHashSet;
 import io.vavr.collection.List;
 import io.vavr.collection.Map;
-import io.vavr.collection.*;
 import io.vavr.collection.PriorityQueue;
 import io.vavr.collection.Queue;
 import io.vavr.collection.Set;
@@ -37,12 +37,10 @@
 import io.vavr.collection.TreeMap;
 import io.vavr.collection.TreeSet;
 import io.vavr.collection.Vector;
-import io.vavr.concurrent.Future;
 import io.vavr.control.Either;
 import io.vavr.control.Option;
 import io.vavr.control.Try;
 import io.vavr.control.Validation;
-
 import java.io.PrintStream;
 import java.io.PrintWriter;
 import java.util.*;

vavr/src/main/java/io/vavr/collection/AbstractMultimap.java

@@ -21,7 +21,6 @@
 import io.vavr.Tuple;
 import io.vavr.Tuple2;
 import io.vavr.control.Option;
-
 import java.io.Serializable;
 import java.util.Collection;
 import java.util.Comparator;

vavr/src/main/java/io/vavr/collection/AbstractQueue.java

@@ -21,7 +21,6 @@
 import io.vavr.Tuple;
 import io.vavr.Tuple2;
 import io.vavr.control.Option;
-
 import java.util.NoSuchElementException;
 import java.util.Objects;
 import java.util.function.Consumer;

vavr/src/main/java/io/vavr/collection/Array.java

@@ -22,7 +22,6 @@
 import io.vavr.collection.ArrayModule.Combinations;
 import io.vavr.collection.JavaConverters.ListView;
 import io.vavr.control.Option;
-
 import java.io.Serializable;
 import java.util.*;
 import java.util.function.*;

vavr/src/main/java/io/vavr/collection/BitMappedTrie.java

@@ -23,11 +23,11 @@
 import java.util.function.Function;
 import java.util.function.Predicate;
 
-import static java.util.function.Function.identity;
 import static io.vavr.collection.ArrayType.obj;
 import static io.vavr.collection.Collections.withSize;
 import static io.vavr.collection.NodeModifier.COPY_NODE;
 import static io.vavr.collection.NodeModifier.IDENTITY;
+import static java.util.function.Function.identity;
 
 /**
  * A `bit-mapped trie` is a very wide and shallow tree (for integer indices the depth will be `≤6`).