Update license plugin to use SLASHSTAR_STYLE for license headers in java files

This change fixes "dangling Javadoc comment" warnings in license headers.
See https://github.com/mycila/license-maven-plugin#supported-comment-types

Author: fmbenhassine

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/AssertFalseAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/AssertTrueAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/BeanValidationAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/BeanValidationRandomizerRegistry.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/DecimalMinMaxAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/EmailAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/FutureAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/FutureOrPresentAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/MinMaxAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

easy-random-bean-validation/src/main/java/org/jeasy/random/validation/NegativeAnnotationHandler.java

@@ -1,4 +1,4 @@
-/**
+/*
  * The MIT License
  *
  *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)