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Changing the version of a transitive dependency in maven pom.xml

I've been trying to override a transitive dependency version in one of my projects. I found the following sample project on github to experiment on ( https://github.com/Richou/swagger-codegen-maven-plugin). The parent pom of this project contains a dependency for swagger-codegen. Swagger-codegen in turn has a dependency called slf4j-ext whose version is 1.6.3. I want to upgrade/override the version of slf4j-ext to 1.7.30 from the parent pom. I tried adding the required slf4j-version inside the property tag in the parent pom but it didn't work when I checked the maven dependency tree. What is the correct method to do it?
<dependency>
<groupId>io.swagger</groupId>
<artifactId>swagger-codegen</artifactId>
<version>2.1.2</version>
</dependency>
</dependencies>
<properties>
<slf4j-version>1.7.30</slf4j-version>
<java.version>1.7</java.version>
</properties>

You can add the slf4j-ext with the version you want in the dependencyManagement section of your parent pom.
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-ext</artifactId>
<version>${slf4j-version}</version>
</dependency>
</dependencies>
</dependencyManagement>

Maven clean install failed to execute goal on project

I am developing a spring boot project which has few modules. I have on entry point module which has main class, the other module dependencis i have added in entry point module pom.xml. When i give command mvn clean install it throws an error saying `
Failed to execute goal on project api: Could not resolve dependencies
for project com.nikesh:api:jar:1.0.0: The following artifacts could
not be resolved: com.nikesh:lib:jar:1.0.0, com.nikesh:repo:jar:1.0.0,
com.nikesh:entity:jar:1.0.0, com.nikesh:dto:jar:1.0.0,
com.nikesh:service:jar:1.0.0, com.nikesh:common:jar:1.0.0: Failure to
find com.nikesh:lib:jar:1.0.0 in https://repo.maven.apache.org/maven2
was cached in the local repository, resolution will not be reattempted
until the update interval of central has elapsed or updates are forced
-`
This is my pom.xml
<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>com.nikesh</groupId>
<artifactId>api</artifactId>
<version>1.0.0</version>
<description>api module</description>
<packaging>jar</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.6.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
<start-class>com.nikesh.api.MultiModuleApp</start-class>
</properties>
<dependencies>
<dependency>
<groupId>com.nikesh</groupId>
<artifactId>lib</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>com.nikesh</groupId>
<artifactId>repo</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>com.nikesh</groupId>
<artifactId>entity</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>com.nikesh</groupId>
<artifactId>dto</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>com.nikesh</groupId>
<artifactId>service</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>com.nikesh</groupId>
<artifactId>common</artifactId>
<version>1.0.0</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
Please help me out resolving this issue.

You need to make sure that all sub modules are built in proper order before the main module build.
Guide to Working with Multiple Modules
The Reactor
The mechanism in Maven that handles multi-module projects is referred to as the reactor. This part of the Maven core does the following:
Collects all the available modules to build
Sorts the projects into the correct build order
Builds the selected projects in order
Because modules within a multi-module build can depend on each other, it is important that The reactor sorts all the projects in a way that guarantees any project is built before it is required.
The following relationships are honoured when sorting projects:
a project dependency on another module in the build
a plugin declaration where the plugin is another modules in the build
a plugin dependency on another module in the build
a build extension declaration on another module in the build
the order declared in the element (if no other rule
applies)
Note that only "instantiated" references are used - dependencyManagement and pluginManagement elements will not cause a change to the reactor sort order
for more info. You can refer this link for a sample multi module maven project.

Maven manage dependencies via another pom

I have two maven projects.
-- my-common-lib
-- my-web-application
my-common-lib - contains just a pom which all dependencies.
my-web-application - is a web application.
Is there a maven plugin which I can define in "my-application" pom that makes that all dependencies defined in "my-common-lib" should not be added to "WEB-INF/lib" when building my-web-application project .
Thanks
Sundar

You can use the following to import dependencies from the other artifact.
<dependencyManagement>
<dependencies>
<dependency>
<groupId>com.sample<groupId>
<artifactId>myartifact</artifactId>
<version>0.0.1</version>
<scope>import</scope>
<type>pom</type>
</dependency>
</dependencies>
</dependencyManagement>

Setting custom runtime classpath for a maven project in netbeans

I want to add a custom classpath when I'm running my maven project from within netbeans. So far I've tried adding the following to the Run Project action in the project properties:
exec.args=-classpath %classpath;c:/QUASR/duplicateRemoval.jar;c:/QUASR/lib/QUASR.jar ${packageClassName}
exec.args=-cp %classpath;c:/QUASR/duplicateRemoval.jar;c:/QUASR/lib/QUASR.jar ${packageClassName}
exec.args=-cp c:/QUASR/duplicateRemoval.jar;c:/QUASR/lib/QUASR.jar ${packageClassName}
but no luck, the custom runtime classpath is not set.

You should add a new profile run-with-netbeans in your pom that declares the additional dependencies (use the provided scope to not include them in the release).
Then you'll have to add the new profile to your IDE to run the pom with the -P run-with-netbeans option in the command line.
<properties>
<!-- provided by default -->
<my-dynamic-scope>provided</my-dynamic-scope>
</properties>
<profiles>
<profile>
<id>run-with-netbeans</id>
<properties>
<!-- compile when running in IDE -->
<my-dynamic-scope>compile</my-dynamic-scope>
</properties>
<dependencies>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
</dependencies>
</profile>
</profiles>
<dependencies>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>${commons-lang.version}</version>
<scope>${my-dynamic-scope}</scope>
</dependency>
</dependencies>
The snippet above add log4j only when running with the run-with-netbeans profile. It also sets a property my-dynamic-scope that can be used in your dependency block to change the scope.
HIH
M.

How to define organization specific parent pom

Env: Maven 2.2.1
I have two java projects under svn (projectA, projectB). My maven structure is as follows..
For projectA
pom.xml (contains ProjectA parent pom definitions)
module moduleA
module moduleB
For projectB
pom.xml (contains ProjectB parent pom definitions)
module moduleC
module moduleD
projectA/pom.xml and projectB/pom.xml contain common definitions like junit, selenium, compiler, eclipse plug-ins which are common to both projects. (e.g. given below)
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>2.4</version>
<type>jar</type>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.7</version>
<scope>test</scope>
</dependency
How should I create / organize a organization specific project pom which includes such common definitions, so that individual projects don't have to re-create / maintain one. Can someone provide some snippets or projects which have already done this before?
EDIT1:
company/pom.xml
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany</groupId>
<artifactId>company</artifactId>
<packaging>pom</packaging>
<name>parent</name>
<version>1.0.0</version>
<build>
<defaultGoal>install</defaultGoal>
</build>
<dependencies>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>2.4</version>
<type>jar</type>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
</dependencies>
projectA/pom.xml
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.mycompany</groupId>
<artifactId>company</artifactId>
<version>1.0.0</version>
</parent>
<groupId>com.mycompany</groupId>
<artifactId>projectA</artifactId>
<packaging>pom</packaging>
<name>projectA</name>
<version>1.0.0</version>
<modules>
<module>moduleA</module>
<build>
<defaultGoal>install</defaultGoal>
</build>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
projectA/moduleA/pom.xml
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.mycompany</groupId>
<artifactId>projectA</artifactId>
<version>1.0.0</version>
<relativePath>../pom.xml</relativePath>
</parent>
<groupId>com.mycompany</groupId>
<artifactId>moduleA</artifactId>
<version>1.0.0</version>
<packaging>jar</packaging>
<name>moduleA</name>
<build>
<finalName>moduleA</finalName>
<defaultGoal>install</defaultGoal>
</build>
<dependencies>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
</dependency>
</dependencies>
Throws the following error:
Project ID: com.mycompany:moduleA
POM Location: c:\temp\maven\projectA\moduleA\pom.xml
Validation Messages:
[0] 'dependencies.dependency.version' is missing for commons-lang:comm
ons-lang:jar
[1] 'dependencies.dependency.version' is missing for javax.servlet:ser
vlet-api:jar

I would seriously reconsider adding dependencies into a "super" POM, this unnecessarily couples the projects (but may hint that if the projects aren't disparate then they should be merged anyway).
I think the last comment by #lexicore is poignant too, to expand on the OOP analogy it also feels like "mixing levels of abstraction".
Alex Gitelman provides the correct answer, you need to use dependencyManagement as shown here Dependency Scope
Maven3 is supposed to be supporting POM fragments see How to use Maven 3 mixins? which I've long been waiting for.
We have an organisation Über POM but this just contains:
<organization>
<name>...</name>
<url>...</url>
</organization>
<developers>
<developer>
<id>...<id>
<name>...</name>
<email>...</email>
<roles>
<role>...</role>
</roles>
</developer>
<distributionManagement>
...
</distributionManagement>
<repositories>
<!-- your proxy repo here -->
</repositories>
These are things that change very rarely (if we change our repository/distribution-management then all projects must change, if a developer leaves or joins we can update the project POMs at any time convenient).
Dependencies belong specifically to the module under consideration, just because two independent project happen to share dependencies now doesn't mean they always will. I completely understand the annoyance of having to copy 'n' paste reams of XML for each project (compiler plugin, reporting plugins, junit etc), but differing levels of activity in each project will surely mean they diverge at some point.
WRT cascade builds in Continuous Integration, if project A demands a change in the super dependencies POM, then all you other projects will be forced to rebuild - maybe fine if you've only 2 projects but even then did you checkout and build both before committing the change?

If it's only dependencies that you need to reuse, create another project with packaging pom and specify dependencies there. Let's call it OrgDependencies Then include it as dependency in your projectA and projectB. It will transitively pull all dependencies from OrgDependencies project.
In your example, in projectA, instead of
<parent>
<groupId>com.mycompany</groupId>
<artifactId>company</artifactId>
<version>1.0.0</version>
</parent>
Try putting
<dependencies>
<dependency>
<groupId>com.mycompany</groupId>
<artifactId>company</artifactId>
<version>1.0.0</version>
</dependency>
</dependencies>
And remove dependencies to commons-lang etc from modules.
Update.
While my previous solution with transitive dependencies should work, actually what you need
is <dependencyManagement> section in your company wide pom.xml
That's where you define versions.
Note: Anything in dependencyManagement section is not really a dependency but just a descriptor that allows to specify version and exclude transitive dependencies (if necessary) in case normal dependencies section specifies that dependency. So you can put as many items in dependencyManagement as you want, it will not make all descendants dependent on them.
I tested it and it works:
<?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/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany</groupId>
<artifactId>company</artifactId>
<packaging>pom</packaging>
<name>parent</name>
<version>1.0.0</version>
<build>
<defaultGoal>install</defaultGoal>
</build>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>commons-lang</groupId>
<artifactId>commons-lang</artifactId>
<version>2.4</version>
<type>jar</type>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
</dependencies>
</dependencyManagement>
</project>

In OS projects I am normally using 3+ levels of POMs:
"Company-wide POM" contains dev-wide definitions like distribution management, individual plugin versions etc. Very stable, normally has one-number version. Example: Sonatype OSS Parent.
"Project POM" contains project-wide definitions: Java compiler version, dependency management etc. Parent is company-wide POM. Example :JAXB2 Basics Project. Version is updated with each release.
"Module POMs" on different levels. List individual dependencies (versions of dependencies are inherited from the project POM), add "special" build steps. Example: JAXB Basics.
I saw a similar pattern an other OS projects (like Apache's) as well.
A few more comments:
You may also have the "department POM" or "product POM" depending on the company size and product organization.
Think of POM inheritance pretty much as of OOP inheritance. What would you put into which abstract class so that class hierarchy is stable but dynamic? For instance, it would not make sense to define versions of dependencies in the company-wide POM since versions change too often. On the contrary, defining distribution management in earch of the projects would hurt the DRY principle.