How to create a zip archive with some readonly files with maven-assembly-plugin - maven

Question

I have a project with 2 files (src/foo/a.txt and src/foo/b.txt) and I want to create a zip archive where b.txt is in readonly.
Here's my environment:
Windows 7
JRE 1.8.0_112
Maven 3.3.3
maven-assembly-plugin 3.0.0
7-Zip 9.20
Here's my pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.foo</groupId>
<artifactId>foo-zip</artifactId>
<version>0.1-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-assembly-plugin</artifactId>
<version>3.0.0</version>
<executions>
<execution>
<phase>package</phase>
<goals><goal>single</goal></goals>
</execution>
</executions>
<configuration>
<encoding>UTF-8</encoding>
<appendAssemblyId>false</appendAssemblyId>
<descriptors>
<descriptor>src/foo-assembly.xml</descriptor>
</descriptors>
</configuration>
</plugin>
</plugins>
</build>
</project>
and here's my assembly descriptor:
<?xml version="1.0" encoding="UTF-8"?>
<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">
<id>foo-zip</id>
<includeBaseDirectory>false</includeBaseDirectory>
<formats><format>zip</format></formats>
<fileSets>
<fileSet>
<directory>src/foo</directory>
<excludes><exclude>b.txt</exclude></excludes>
<outputDirectory />
</fileSet>
<fileSet>
<directory>src/foo</directory>
<includes><include>b.txt</include></includes>
<fileMode>0444</fileMode>
<outputDirectory />
</fileSet>
</fileSets>
</assembly>
When I unzip the generated archive, and open the properties of b.txt, the "readonly" checkbox is not checked.
I'm aware of:
Maven assembly plugin not applying fileMode on unpacked dependencySet and maven assembly plugin do not set file attributes but they haven't helped me much.
I tried various fileMode values (0444 or 0544) but I just can't get my file to be uncompressed in readonly mode.
Any ideas?