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Move a folder generated inside "target/bla/bla/bla" to "src\main\java\com\demo\project" using Maven/POM.xml

I am using a (Swagger) OpenApi YAML spec to generate Client Java code (much like creating SOAP client using WSDL file)
In my eclipse I am doing project (right click) -> Run -> Maven Build... (Set goal as "generate-sources" and profile as "codegen")
This is creating the "folder" inside target folder which has my client JAVA (.java) code.
I need to move it to the "src" to a specific folder.
This is my POM.xml
<profile>
<id>codegen</id>
<build>
<plugins>
<plugin>
<groupId>org.openapitools</groupId>
<artifactId>openapi-generator-maven-plugin</artifactId>
<version>5.0.0</version>
<executions>
<execution>
<goals>
<goal>generate</goal>
</goals>
<id>generate-sources</id>
<phase>generate-sources</phase>
<configuration>
<inputSpec>${project.basedir}/src/main/resources/ClientSideJavaCode.yaml</inputSpec>
<generatorName>java</generatorName>
<packageName>com.demo.project.test.rest.generated</packageName>
<apiPackage>com.demo.project.test.rest.generated.api</apiPackage>
<modelPackage>com.demo.project.test.rest.generated.model</modelPackage>
<configOptions>
<sourceFolder>src/java/main</sourceFolder>
</configOptions>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
What should I change/add to make it work? Will copy-resource plugin work?

Don't
The build should only write to the target directory.
Everything else will mess up your git/svn.
The generated source code should go to target and be compiled from there.

Automatically generate Java from .proto with maven/m2e in Eclipse IDE

For my team, I'd like to configure maven/eclipse build to automatically generate Java code from *.proto files (in a project that uses gRPC). Currently one needs to run mvn generate-source or mvn protobuf:compile (as in plugin usage page). Or what is the same add Run configuration to invoke maven goal compile.
Whenever Eclipse Maven project is refreshed (Alt+F5) or IDE is restarted, project is rebuilt but without what should appear in target/generated, thus turning project into red. So one need to generate and refresh project (F5). UPDATE Eclipse has needed source folders configured in .clathpath file.
As I know that should be m2e connector, but I could only find one https://github.com/masterzen/m2e-protoc-connector for the oldest Googles plugin com.google.protobuf.tools:maven-protoc-plugin, that is even not mentioned currently at https://github.com/grpc/grpc-java
We use exactly referenced/recommended
<groupId>org.xolstice.maven.plugins</groupId>
<artifactId>protobuf-maven-plugin</artifactId>
that is:
<build>
<extensions>
<extension>
<groupId>kr.motd.maven</groupId>
<artifactId>os-maven-plugin</artifactId>
<version>1.4.1.Final</version>
</extension>
</extensions>
<plugins>
<plugin>
<groupId>org.xolstice.maven.plugins</groupId>
<artifactId>protobuf-maven-plugin</artifactId>
<version>0.5.0</version>
<configuration>
<protocArtifact>com.google.protobuf:protoc:3.1.0:exe:${os.detected.classifier}</protocArtifact>
<pluginId>grpc-java</pluginId>
<pluginArtifact>io.grpc:protoc-gen-grpc-java:1.0.1:exe:${os.detected.classifier}</pluginArtifact>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>compile-custom</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Related:
Linking to generated Java protobuf code in Eclipse
looked at this but that author was using other older, not supported now plugin : Eclipse build loop caused by protobuf generated code (related to Maven Project Builder)
P.P.S That plugin https://github.com/igor-petruk/protobuf-maven-plugin however has continuation as https://github.com/os72/protoc-jar-maven-plugin

Instead of using org.xolstice.maven.plugins:protobuf-maven-plugin my team has used com.github.os72:protoc-jar-maven-plugin to generate the message classes. I believe they are the same since under the hood they all seem to be using the tools from Google.
I am not using any m2e connectors for this plugin (Edit: protoc-jar-maven-plugin's m2e connector is bundled with it so no extra installation is needed, which is why it seemed like I wasn't using one, but technically I was, but this doesn't really matter). Unfortunately the changes in the .proto file are not "automatically" propagated to the generated .java files, you need to manually run Maven or trigger the project to be built in Eclipse (instructions below), but fortunately the target/generated-sources file is not vanishing or emptying or anything strange like what you describe.
If you want to rebuild the .java files from the .proto classes without using mvn clean compile from the command line you can clean the Eclipse project . Project → Clean... → select your project → Select build option (only shows if you have "Build Automatically" from the Project menu is unchecked).
I was able to do this in the latest Eclipse Neon (it will probably work in later ones too, but I don't know for certain).
Below is the POM I am using. I don't think it requires any special explanation, my solution is to simply use a different plugin than the one you are using. (If some explanation is needed I'll be happy to provide it though.)
<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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>io.github.jacksonbailey</groupId>
<artifactId>protobuf-m2e-sample</artifactId>
<version>0.1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.1.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>com.github.os72</groupId>
<artifactId>protoc-jar-maven-plugin</artifactId>
<version>3.1.0.1</version>
<executions>
<execution>
<phase>generate-sources</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<protocVersion>3.1.0</protocVersion>
<inputDirectories>
<include>src/main/resources</include>
</inputDirectories>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>

for protobuf-maven-plugin
Thanks to sergei-ivanov answer in https://github.com/xolstice/protobuf-maven-plugin/issues/16, that gave link https://github.com/trustin/os-maven-plugin#issues-with-eclipse-m2e-or-other-ides :
One need to download os-maven-plugin-x.x.x.Final.jar (the version as in your pomx.ml) and put it into the <ECLIPSE_HOME>/plugins directory.
After that Eclipse will generate source on project clean, including after Maven -update project... (Alt+F5), but not after Project -> Build (or with default Build Automatically). Also on IDE start it will not compile.
Yes, that is illogical:
Project - Clean will generate and compile Java source
but
Project - Build will not.
P.S. Raised Bug 507412

Both eclipse and vscode can automatically compile proto when changed.
<plugin>
<groupId>kr.motd.maven</groupId>
<artifactId>os-maven-plugin</artifactId>
<version>1.6.2</version>
<executions>
<execution>
<phase>initialize</phase>
<goals>
<goal>detect</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.xolstice.maven.plugins</groupId>
<artifactId>protobuf-maven-plugin</artifactId>
<version>0.6.1</version>
<configuration>
<protocArtifact>com.google.protobuf:protoc:3.12.0:exe:${os.detected.classifier}</protocArtifact>
<pluginId>grpc-java</pluginId>
<pluginArtifact>io.grpc:protoc-gen-grpc-java:1.32.1:exe:${os.detected.classifier}</pluginArtifact>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>compile-custom</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.1</version>
<configuration>
<source>8</source>
<target>8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
See: https://github.com/trustin/os-maven-plugin#issues-with-eclipse-m2e-or-other-ides

maven generated jaxb classes - ClassNotFoundException

I have a maven model project, where I am generating jaxb class by maven command - clean install
and the jaxb classes are generated under target folder and jar file is generating under .m2 repository folder.
Now on my other project adding this jar as a dependency with proper group id and artifactId.
But I am getting ClassNotFoundException and compile error for those generated jaxb classes.
I am updating my question to add more details.
The Pom File of Model Project.
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.5.1</version>
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<groupId>org.jvnet.jaxb2.maven2</groupId>
<artifactId>maven-jaxb2-plugin</artifactId>
<version>0.8.3</version>
<executions>
<execution>
<id>spf-ssp-generate</id>
<goals>
<goal>generate</goal>
</goals>
<configuration>
<generateDirectory>${project.build.directory}/jaxbclasses/pqr/xyz</generateDirectory>
<generatePackage>abc.vo.apply.v1</generatePackage>
<schemaIncludes>
<include>MyXSD.xsd</include>
</schemaIncludes>
</configuration>
</execution>
</executions>
<configuration>
<schemaDirectory>src/main/resources</schemaDirectory>
<extension>true</extension>
<args>
<arg>-XtoString</arg>
<arg>-Xequals</arg>
<arg>-XhashCode</arg>
</args>
<plugins>
<plugin>
<groupId>org.jvnet.jaxb2_commons</groupId>
<artifactId>jaxb2-basics</artifactId>
<version>0.6.4</version>
</plugin>
</plugins>
</configuration>
</plugin>
</plugins>
</build>
On clean install it generates the class files under.
target
jaxbclasses
pqr
xyz
with the package name - abc.vo.apply.v1
I have another Two Maven project(jar), suppose as, A & B.
Now I can use the jaxb model project as a maven dependency, and it compile fine.
Now My Web project is not a Maven project - it is a Liferay based on Ant.
I manually copy the A, B and The Jaxb Model project in to lib folder.
It compile fines. but I am getting ClassNotFoundException.

I am adding another answer, which I think is more accurate.
In order to make your JAXB project compile, I had to add this dependency:
<dependency>
<groupId>org.jvnet.jaxb2_commons</groupId>
<artifactId>jaxb2-basics</artifactId>
<version>0.6.5</version>
</dependency>
which obviously won't be automatically part of your classpath for Liferay.
When I ran mvn dependency:list, I got this:
org.jvnet.jaxb2_commons:jaxb2-basics-tools:jar:0.6.4:compile
org.jvnet.jaxb2_commons:jaxb2-basics:jar:0.6.4:compile
commons-lang:commons-lang:jar:2.2:compile
commons-logging:commons-logging:jar:1.1.1:compile
com.google.code.javaparser:javaparser:jar:1.0.8:compile
org.jvnet.jaxb2_commons:jaxb2-basics-runtime:jar:0.6.4:compile
commons-beanutils:commons-beanutils:jar:1.7.0:compile`
which means that you need to put these in the lib directory of your Liferay installation as well.

This is most likely due to the fact that the target directory is never included in the jar file by default. Try configuring the JAXB classes to be generated under (say) target/generated. Then, add this to the build plugin section of the POM:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.9.1</version>
<executions>
<execution>
<id>add-java-sources</id>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>${project.build.directory}/generated</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>

Is it possible to compile grunt project from maven?

I'm trying to execute grunt tasks from within maven without needing to install Node.js or anything. This is because I wan't my artifact to be packaged by Jenkins and I can't install Node.js on that machine.
I know that it's easy with npm and a few commands to get it working, but I also think that it should be easy to integrate with maven, the problem is that I don't know where to start since I'm new to npm.

Yes, using the frontend-maven-plugin, you can compile Grunt projects via Maven (found via the NodeJS mailing list).
As the documentation points out, the plugin has the following features:
Let you keep your frontend and backend builds as separate as possible, by reducing the amount of interaction between them to the bare minimum; using only 1 plugin.
Let you use Node.js and its libraries in your build process without installing Node/NPM globally for your build system
Let you ensure that the version of Node and NPM being run is the same in every build environment
I've walked through the code and it's fairly simple. Thank goodness someone finally put this together; it's an elegant solution. The repository includes an example that uses a regular Gruntfile.js to invoke jshint analysis.

UPDATE 2014-09-19: This is no longer the most accurate answer - please take a look at some of the other answers below. It was accurate at the time when I answered the question, but there seems to have been a good deal of progress in this area since then.
I'm afraid you're out of luck. Grunt is built using node and needs to be installed using npm. You might be able to copy an existing installation of Grunt from another machine if you don't want to use npm, but will still use the grunt executable and all of its dependencies on your build server.
In addition to that, many of the Grunt tasks are implemented as Node.js modules, and you will have to install them as well. Again, you might be able to copy them from another server, where you've done the Node.js/Grunt installation, but at one point, you have to do it.
For running Grunt from Maven, your best bet is to use the Maven exec plugin and then execute the grunt executable from there.
As an alternative, there are several Maven plugins that allow you to do things similar to Grunt in a Java-based fashion. They require additional configuration not compatible with Grunt, so YMMV. One that I've used in the past is http://code.google.com/p/wro4j/, which comes with a Maven plugin as well: http://code.google.com/p/wro4j/wiki/MavenPlugin
Any particular reason why you can't install Node.js on your build server?

You can use grunt-maven-plugin. It allows you to easily integrate Grunt tasks into Maven build process. No dirty hacks.
This is what I use in my current project and it works just perfect.

Finally I ended up with this (which is close enough but doesn't solve the problem):
<plugin>
<groupId>org.mule.tools.javascript</groupId>
<artifactId>npm-maven-plugin</artifactId>
<version>1.0</version>
<executions>
<execution>
<phase>generate-resources</phase>
<goals>
<goal>fetch-modules</goal>
</goals>
<configuration>
<packages>
<package>grunt-cli:0.1.6</package>
</packages>
</configuration>
</execution>
</executions>
</plugin>
that installs locally the grunt-cli, but if I don't have installed node.js it's worthless. Although I try to install node.js locally there's the need to have installed python, g++ and make. So I'll go with the KISS solution: install grunt in the build server.
References:
https://github.com/mulesoft/npm-maven-plugin
https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager
https://github.com/mcheely/requirejs-maven-plugin

You might want to checkout http://jhipster.github.io/ : it's a Yeoman generator, that generates an application which has Maven, Grunt and Bower all working together.
It's a bit like your third option, but everything is configured for you, which isn't that easy. It's also generating the basic AngularJS and Java REST services for you

This is a full copy/paste solution which work in 2017 using frontend-maven-plugin for front build, and maven-war-plugin to build the war.
What it does ? install npm, bower grunt,and everything you need, then run npm install, bower install and finally grunt build.
You can remove/add replace the steps you want, for me it's a full 30 sec install/build library and project.
<dependencies>
...
</dependencies>
<dependencyManagement>
<dependencies>
<!-- https://mvnrepository.com/artifact/com.github.eirslett/frontend-maven-plugin -->
<dependency>
<groupId>com.github.eirslett</groupId>
<artifactId>frontend-maven-plugin</artifactId>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.4</version>
<configuration>
<warSourceDirectory>src/main/webapp/YourFrontJsFolder/dist</warSourceDirectory>
<warName>YouWarName</warName>
<failOnMissingWebXml>false</failOnMissingWebXml>
<warSourceExcludes>node_modules/**</warSourceExcludes>
<includeScope>system</includeScope>
<webResources>
<resource>
<directory>WebContent/WEB-INF</directory>
<targetPath>WEB-INF</targetPath>
<includes>
<include>**/*.jar</include>
<include>**/*.jsp</include>
</includes>
</resource>
</webResources>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<encoding>Cp1252</encoding>
</configuration>
</plugin>
</plugins>
</pluginManagement>
<finalName>YourAppName</finalName>
</build>
<profiles>
<profile>
<id>release</id>
<build>
<plugins>
<plugin>
<groupId>com.github.eirslett</groupId>
<artifactId>frontend-maven-plugin</artifactId>
<executions>
<execution>
<!-- optional: you don't really need execution ids, but it looks
nice in your build log. -->
<id>install node and npm</id>
<goals>
<goal>install-node-and-npm</goal>
</goals>
<!-- optional: default phase is "generate-resources" -->
<phase>generate-resources</phase>
<configuration>
<nodeVersion>v7.6.0</nodeVersion>
</configuration>
</execution>
<execution>
<id>npm install</id>
<goals>
<goal>npm</goal>
</goals>
<!-- optional: default phase is "generate-resources" -->
<phase>generate-resources</phase>
<configuration>
<arguments>install</arguments>
</configuration>
</execution>
<execution>
<id>bower install</id>
<goals>
<goal>bower</goal>
</goals>
<configuration>
<!-- optional: The default argument is actually "install", so unless
you need to run some other bower command, you can remove this whole <configuration>
section. -->
<arguments>install</arguments>
</configuration>
</execution>
<execution>
<id>grunt build</id>
<goals>
<goal>grunt</goal>
</goals>
<!-- optional: the default phase is "generate-resources" -->
<phase>generate-resources</phase>
<configuration>
<!-- optional: if not specified, it will run Grunt's default task
(and you can remove this whole <configuration> section.) -->
<arguments>build</arguments>
</configuration>
</execution>
</executions>
<configuration>
<installDirectory>target</installDirectory>
<workingDirectory>src/main/webapp/YourFrontJsFolder</workingDirectory>
</configuration>
</plugin>
</plugins>
</build>
</profile>
<profile>
<id>debug</id>
<activation>
<activeByDefault>true</activeByDefault>
</activation>
</profile>
<profile>
<id>IDE</id>
<activation>
<property>
<name>m2e.version</name>
</property>
</activation>
<build>
<!-- Put the IDE's build output in a folder other than target, so that
IDE builds don't interact with Maven builds -->
<directory>target-ide</directory>
</build>
</profile>
</profiles>
Then you can Run as -> Maven build ..., with goal clean install and profile release

The first problem is that Maven is Java, but Grunt.js runs on the Node.js runtime. The easiest integration I ever achieved between the two involved the maven-exec-plugin. The maven-exec-plugin is capable of executing .sh/.bat/.cmd scripts, whichever are native to the OS you are using. So during a Maven build I would have the maven-exec-plugin execute a script named optimize-js.sh, for example, which would simply do something like “grunt release –force”, or whatever. The scripts can be made to do whatever. The important thing is to configure the maven-exec-plugin to execute them in the correct working directory. Of course, “grunt” and “node” need to be executable from the command-line.

If the problem is installing NodeJS on the Jenkins machine then you can use the NodeJS Jenkins plugin.
https://wiki.jenkins-ci.org/display/JENKINS/NodeJS+Plugin
We're not using it with Maven (yet) but we've got grunt running.

Can be done with exec-maven-plugin.
Define a script and dependency to grunt-cli in your package.json:
...
"scripts": {
"build": "./node_modules/.bin/grunt install"
},
"devDependencies": {
"grunt-cli": "^1.2.0",
...
In your pom, add the commands to run:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>X.Y.Z</version>
<executions>
<execution>
<id>exec-npm-install</id>
<phase>generate-sources</phase>
<configuration>
<workingDirectory>${project.basedir}</workingDirectory>
<executable>npm</executable>
<arguments>
<argument>install</argument>
</arguments>
</configuration>
<goals>
<goal>exec</goal>
</goals>
</execution>
<execution>
<id>exec-grunt-install</id>
<phase>generate-sources</phase>
<configuration>
<workingDirectory>${project.basedir}</workingDirectory>
<executable>npm</executable>
<arguments>
<argument>run</argument>
<argument>build</argument>
</arguments>
</configuration>
<goals>
<goal>exec</goal>
</goals>
</execution>
</executions>
</plugin>
It will now run on mvn package

Maven add jars through systemPath/system but not added to war or anywhere else

I want to add a jar file through the systemPath from the local file-system relative to my project directory structure, not on a remote repository. I added the dependency declaration but maven doesn't do anything else with it.
In the declaration below, I want the jar file copied to my target web-inf/lib directory and also jarred as part of the war file. At present, that doesn't happen. How would I get the jar file copied to my war file?
This is the output from debug maven mode:
DEBUG] cglib:cglib-nodep:jar:2.2:test (setting scope to: compile)^M
DEBUG] Retrieving parent-POM: org.objenesis:objenesis-parent:pom:1.2 for project: null:objenesis:ja
DEBUG] org.objenesis:objenesis:jar:1.2:test (selected for test)^M
DEBUG] org.javap.web:testRunWrapper:jar:1.0.0:system (selected for system)^M
DEBUG] Plugin dependencies for:
...
<dependency>
<groupId>org.javap.web</groupId>
<artifactId>testRunWrapper</artifactId>
<version>1.0</version>
<scope>system</scope>
<systemPath>${basedir}/lib/testRunWrapper.jar</systemPath>
</dependency>
<plugin>
<artifactId>maven-war-plugin</artifactId>
<configuration>
<webResources>
<resource>
<directory>WebContent</directory>
</resource>
</webResources>
</configuration>
</plugin>

OK, I did this: Note the directory structure at the bottom.
With the approach below, the jar file from the relative project path is treated as a first class citizen like the other jars. The listing below corrects my original problem. With the pom.xml listing below, the jar file is copied to my target directory.
<repositories>
<repository>
<id>JBoss</id>
<name>JBoss Repository</name>
<layout>default</layout>
<url>http://repository.jboss.org/maven2</url>
</repository>
<repository>
<id>my-local-repo</id>
<url>file://${basedir}/lib/repo</url>
</repository>
</repositories>
<dependency>
<groupId>testRunWrapper</groupId>
<artifactId>testRunWrapper</artifactId>
<version>1.0.0</version>
</dependency>
$ find repo
repo
repo/testRunWrapper
repo/testRunWrapper/testRunWrapper
repo/testRunWrapper/testRunWrapper/1.0.0
repo/testRunWrapper/testRunWrapper/1.0.0/testRunWrapper-1.0.0.jar

Using the maven dependency plugin does the job:
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.8</version>
<executions>
<execution>
<id>copy-dependencies</id>
<phase>compile</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/lib</outputDirectory>
<includeScope>system</includeScope>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>

Don't use system. To do what you want, just declare as a regular (compile) dependency and use mvn install:install-file into your local repository. Everything else will work as you want (lib will be copied, etc.) That will mean that the build will only work on your machine, however.
To properly fix this for your (internal) team, you will want to set up a repository (e.g. Artifactory, Nexus, or Archiva). This is almost a must for team use of Maven.
If this is for public (e.g. open source) use you can either mimic a repository via an http server or put up a real repository.

try something like this (using Ant plugin to manually put the jar to output directory):
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<executions>
<execution>
<phase>test</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<tasks>
<copy file="${project.basedir}/pathToJAR.jar"
todir="${project.build.directory}/outputFileName/WEB-INF/lib"/>
</tasks>
</configuration>
</execution>
</executions>
</plugin>

AFAIK, system scoped dependencies are somewhat like those with provided scope and thus are not included in the target artifact. Why don't you install the dependency into your local repository instead?
From the doc:
system
This scope is similar to provided except that you have to provide the JAR which contains it explicitly. The artifact is always available and is not looked up in a repository.

In case this answer didn't work for you as it didn't for me and you know that system is a bad scope, you can try this solution where you are Installing the jar by using install-plugin (scroll down a bit), which installs the JAR into your actual local Maven-repository. Basically you only need to add this plugin to your pom.xml:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<phase>initialize</phase>
<goals>
<goal>install-file</goal>
</goals>
<configuration>
<groupId>myGroupId</groupId>
<artifactId>myArtifactId</artifactId>
<version>myVersion</version>
<packaging>jar</packaging>
<file>${basedir}/lib/xxx.jar</file>
</configuration>
</execution>
</executions>
</plugin>
Fill in the appropriate values for groupId, artifactId and version and put your original jar file into the <project-home>/lib-directory and fix file above. You can add more execution-sections, but then don't forget to add ids there, like:
<execution>
<id>common-lib</id>
Everybody who updates from the code-repo needs to call mvn initialize once.
And all Eclipse-enthusiasts may add this to pom.xml, too, to get rid of errors in Eclipse:
<pluginManagement>
<plugins>
<!-- This plugin's configuration is used to store Eclipse m2e settings
only. It has no influence on the Maven build itself. -->
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<versionRange>[2.4,)</versionRange>
<goals>
<goal>install-file</goal>
</goals>
</pluginExecutionFilter>
<action>
<execute></execute>
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
</plugins>
</pluginManagement>

The problem with using a reference to the file system is that dependent projects will not be able to globally access this jar file. i.e. the dependent project's ${basedir} is different and thus the .jar file won't be found.
Global repositories on the other hand are universally accessible.