Support double slash within DOUBLE_SLASH style

Closes #26

src/functionalTest/groovy/org/cadixdev/gradle/licenser/LicenserPluginFunctionalTest.groovy

@@ -446,4 +446,50 @@ class LicenserPluginFunctionalTest extends Specification {
         [gradleVersion, _, extraArgs] << testMatrix
 
     }
+
+    @Unroll
+    def "supports URL in header (gradle #gradleVersion)"() {
+        given:
+        def projectDir = temporaryFolder.newFolder()
+        def sourcesDir = projectDir.toPath().resolve(Paths.get("src", "main", "java")).toFile()
+        sourcesDir.mkdirs()
+        new File(projectDir, "settings.gradle") << ""
+        new File(projectDir, "header.txt") << """
+            Copyright header
+            http://example.com/path?query=value#fragment
+        """.stripIndent().trim()
+        def sourceFile = new File(sourcesDir, "MyClass.java") << "public class MyClass {}"
+        new File(projectDir, "build.gradle") << """
+            plugins {
+                id('java')
+                id('org.cadixdev.licenser')
+            }
+
+            license {
+                header = project.file("header.txt")
+                style {
+                    java = 'DOUBLE_SLASH'
+                }
+            }
+        """.stripIndent()
+
+        when:
+        def runner = runner(projectDir, gradleVersion, extraArgs + "updateLicenses")
+        runner.debug = true
+        def result = runner.build()
+
+        then:
+        result.task(":updateLicenses").outcome == TaskOutcome.SUCCESS
+        sourceFile.text == """\
+            //
+            // Copyright header
+            // http://example.com/path?query=value#fragment
+            //
+
+            public class MyClass {}
+            """.stripIndent()
+
+        where:
+        [gradleVersion, _, extraArgs] << testMatrix
+    }
 }

src/main/groovy/org/cadixdev/gradle/licenser/header/CommentHeaderFormat.groovy

@@ -24,12 +24,14 @@
 
 package org.cadixdev.gradle.licenser.header
 
+import groovy.transform.CompileStatic
 import groovy.transform.PackageScope
 import org.cadixdev.gradle.licenser.util.HeaderHelper
 
 import javax.annotation.Nullable
 import java.util.regex.Pattern
 
+@CompileStatic
 class CommentHeaderFormat implements HeaderFormat {
 
     final String name
@@ -40,13 +42,15 @@ class CommentHeaderFormat implements HeaderFormat {
     @Nullable
     final Pattern skipLine
 
+    @Nullable
     final String firstLine
     final String prefix
+    @Nullable
     final String lastLine
 
     @PackageScope
     CommentHeaderFormat(String name, Pattern start, @Nullable Pattern end, @Nullable Pattern skipLine,
-                        String firstLine, String prefix, String lastLine) {
+                        @Nullable String firstLine, String prefix, @Nullable String lastLine) {
         this.name = name
         this.start = start
         this.end = end
@@ -60,18 +64,19 @@ class CommentHeaderFormat implements HeaderFormat {
         ensureAbsent(text, firstLine)
         ensureAbsent(text, lastLine)
 
-        List<String> result = [firstLine]
+        List<String> result = firstLine == null ? [prefix]: [firstLine]
 
         text.eachLine {
             result << HeaderHelper.stripTrailingIndent("$prefix $it")
         }
 
-        result << lastLine
+        result << (lastLine == null ? prefix : lastLine)
+
         return result
     }
 
     private static void ensureAbsent(String s, String search) {
-        if (s.contains(search)) {
+        if (search != null && s.contains(search)) {
             throw new IllegalArgumentException("Header contains unsupported characters $search")
         }
     }

src/main/groovy/org/cadixdev/gradle/licenser/header/HeaderStyle.groovy

@@ -31,16 +31,16 @@ enum HeaderStyle {
     BLOCK_COMMENT(~/^\s*\/\*(?:[^*].*)?$/, ~/\*\/\s*(.*?)$/, null, '/*', ' *', ' */',
         'java', 'groovy', 'scala', 'kt', 'kts', 'gradle', 'css', 'js'),
     JAVADOC(~/^\s*\/\*\*(?:[^*].*)?$/, ~/\*\/\s*(.*?)$/, null, '/**', ' *', ' */'),
-    HASH(~/^\s*#/, null, ~/^\s*#!/, '#', '#', '#', 'properties', 'yml', 'yaml', 'sh'),
+    HASH(~/^\s*#/, null, ~/^\s*#!/, null, '#', null, 'properties', 'yml', 'yaml', 'sh'),
     XML(~/^\s*<!--/, ~/-->\s*(.*?)$/, ~/^\s*<(?:\?xml .*\?|!DOCTYPE .*)>\s*$/, '<!--', '   ', '-->',
             'xml', 'xsd', 'xsl', 'fxml', 'dtd', 'html', 'xhtml'),
-    DOUBLE_SLASH(~/^\s*\/\//, null, null, '//', '//', '//')
+    DOUBLE_SLASH(~/^\s*\/\//, null, null, null, '//', null)
 
     final CommentHeaderFormat format
     private final String[] extensions
 
     HeaderStyle(Pattern start, @Nullable Pattern end, @Nullable Pattern skipLine,
-                String firstLine, String prefix, String lastLine, String... extensions) {
+                @Nullable String firstLine, String prefix, @Nullable String lastLine, String... extensions) {
         this.format = new CommentHeaderFormat(this.name(), start, end, skipLine, firstLine, prefix, lastLine)
         this.extensions = extensions
     }

src/test/groovy/org/cadixdev/gradle/licenser/header/HeaderStyleTest.groovy

@@ -0,0 +1,70 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015, Minecrell <https://github.com/Minecrell>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package org.cadixdev.gradle.licenser.header
+
+import spock.lang.Specification
+import spock.lang.Unroll
+
+class HeaderStyleTest extends Specification {
+    @Unroll
+    def "test header style #style"() {
+        when:
+        def lines = style.format.format("Test")
+
+        then:
+        lines == expectedLines
+
+        where:
+        [style, expectedLines] << [
+                [HeaderStyle.BLOCK_COMMENT, ["/*", " * Test", " */"]],
+                [HeaderStyle.JAVADOC, ["/**", " * Test", " */"]],
+                [HeaderStyle.DOUBLE_SLASH, ["//", "// Test", "//"]],
+                [HeaderStyle.HASH, ["#", "# Test", "#"]],
+                [HeaderStyle.XML, ["<!--", "    Test", "-->"]]
+        ]
+    }
+
+    def "DOUBLE_SLASH may contain slashes"() {
+        given:
+        HeaderStyle style = HeaderStyle.DOUBLE_SLASH
+
+        when:
+        def lines = style.format.format("// Test //")
+
+        then:
+        lines == ["//", "// // Test //", "//"]
+    }
+
+    def "BLOCK_COMMENT may not contain end of comment"() {
+        given:
+        HeaderStyle style = HeaderStyle.BLOCK_COMMENT
+
+        when:
+        style.format.format("/* Test */")
+
+        then:
+        thrown(IllegalArgumentException)
+    }
+}