Custom Header Styles

The plugin allows you to define entirely new comment styles — either in external XML files or inline in the POM. This is useful when working with file types that use a comment syntax not covered by the built-in styles.

Inline Header Styles

Define new styles directly in pom.xml using <defaultInlineHeaderStyles>:

<configuration>
  <mapping>
    <txt>SMILEY_STYLE</txt>
  </mapping>
  <defaultInlineHeaderStyles>
    <defaultInlineHeaderStyle>
      <name>SMILEY_STYLE</name>
      <firstLine>:(</firstLine>
      <beforeEachLine> ( </beforeEachLine>
      <endLine>:(</endLine>
      <firstLineDetectionPattern>\:\(</firstLineDetectionPattern>
      <lastLineDetectionPattern>\:\(</lastLineDetectionPattern>
      <allowBlankLines>false</allowBlankLines>
      <multiLine>false</multiLine>
    </defaultInlineHeaderStyle>
  </defaultInlineHeaderStyles>
</configuration>

Alternatively, inline styles can be scoped to a single license set via <inlineHeaderStyles>:

<licenseSets>
  <licenseSet>
    <header>com/mycila/maven/plugin/license/templates/APACHE-2.txt</header>
    <inlineHeaderStyles>
      <inlineHeaderStyle>
        <name>MY_STYLE</name>
        <!-- ... -->
      </inlineHeaderStyle>
    </inlineHeaderStyles>
  </licenseSet>
</licenseSets>

External Header Definition Files

For reusable definitions across projects, define styles in an XML file and reference it:

<configuration>
  <headerDefinitions>
    <headerDefinition>src/etc/my-styles.xml</headerDefinition>
  </headerDefinitions>
  <mapping>
    <cs>CSREGION_STYLE</cs>
  </mapping>
</configuration>

Or at the license set level:

<licenseSet>
  <headerDefinitions>
    <headerDefinition>src/etc/my-styles.xml</headerDefinition>
  </headerDefinitions>
</licenseSet>

The definition file is an XML file containing one or more style definitions:

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
  <csregion_style>
    <firstLine>#region LicenseEOL/**</firstLine>
    <beforeEachLine> * </beforeEachLine>
    <endLine> */EOL#endregion</endLine>
    <firstLineDetectionPattern>#region.*^EOL/\*\*.*$</firstLineDetectionPattern>
    <lastLineDetectionPattern>\*/EOL#endregion"</lastLineDetectionPattern>
    <allowBlankLines>true</allowBlankLines>
    <multiLine>true</multiLine>
  </csregion_style>
</additionalHeaders>

Style Definition Fields

Field	Required	Description
firstLine	Yes	The opening line of the comment block
endLine	Yes	The closing line of the comment block
beforeEachLine	No	Characters prepended to each header content line
afterEachLine	No	Characters appended to each header content line
skipLine	No	Regex for a line at the top of the file that must be skipped (e.g., <?xml ...>)
firstLineDetectionPattern	Yes	Regex to detect the start of an existing header
lastLineDetectionPattern	Yes	Regex to detect the end of an existing header
allowBlankLines	No	Whether blank lines are permitted inside the header block (default: false)
multiLine	Yes	true for block comments (/* */), false for line comments (# ...)
padLines	No	For non-multiLine styles: pad each line so all afterEachLine markers align (default: false)

EOL Token

Use EOL in firstLine and endLine to represent the correct platform line separator. For example, <!--EOL produces <!--\n before the first content line.

Example: C# Region Block

Header definition (csregion_style.xml):

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
  <csregion_style>
    <firstLine>#region LicenseEOL/**</firstLine>
    <beforeEachLine> * </beforeEachLine>
    <endLine> */EOL#endregion</endLine>
    <firstLineDetectionPattern>#region.*^EOL/\*\*.*$</firstLineDetectionPattern>
    <lastLineDetectionPattern>\*/EOL#endregion"</lastLineDetectionPattern>
    <allowBlankLines>true</allowBlankLines>
    <multiLine>true</multiLine>
  </csregion_style>
</additionalHeaders>

POM configuration:

<configuration>
  <headerDefinitions>
    <headerDefinition>csregion_style.xml</headerDefinition>
  </headerDefinitions>
  <mapping>
    <cs>CSREGION_STYLE</cs>
  </mapping>
</configuration>

Resulting header in .cs files:

#region License
/**
 * Copyright (C) 2024 Acme Corp
 *
 * Licensed under the Apache License, Version 2.0
 */
#endregion

Example: Built-in Javadoc Style (Reference)

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
  <javadoc_style>
    <firstLine>/**</firstLine>
    <beforeEachLine> * </beforeEachLine>
    <endLine> */</endLine>
    <afterEachLine></afterEachLine>
    <firstLineDetectionPattern>(\s|\t)*/\*.*$</firstLineDetectionPattern>
    <lastLineDetectionPattern>.*\*/(\s|\t)*$</lastLineDetectionPattern>
    <allowBlankLines>false</allowBlankLines>
    <multiLine>true</multiLine>
    <padLines>false</padLines>
  </javadoc_style>
</additionalHeaders>

Example: Built-in XML Style (Reference)

<?xml version="1.0" encoding="ISO-8859-1"?>
<additionalHeaders>
  <xml_style>
    <firstLine><![CDATA[<!--\n]]></firstLine>
    <beforeEachLine>    </beforeEachLine>
    <endLine><![CDATA[-->]]></endLine>
    <afterEachLine></afterEachLine>
    <skipLine><![CDATA[^<\?xml.*>$]]></skipLine>
    <firstLineDetectionPattern><![CDATA[(\s|\t)*<!--.*$]]></firstLineDetectionPattern>
    <lastLineDetectionPattern><![CDATA[.*-->(\s|\t)*$]]></lastLineDetectionPattern>
    <allowBlankLines>false</allowBlankLines>
    <multiLine>true</multiLine>
    <padLines>false</padLines>
  </xml_style>
</additionalHeaders>

All built-in styles can be browsed in the test resources on GitHub.