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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>

How to include multiple jar in type from type field in pom dependency?

I have the following pom definition
<dependencies>
<dependency>
<groupId>com.my.stuff</groupId>
<artifactId>my-stuff</artifactId>
<version>${my-stuff.version}</version>
<type>test-jar</type>
</dependency>
I want to use both jar and test-jar , is there a way to do that?

I guess that test-jar is not a type, but a classifier. You probably want something like:
<dependencies>
<dependency>
<groupId>com.my.stuff</groupId>
<artifactId>my-stuff</artifactId>
<version>${my-stuff.version}</version>
<classifier>test-jar</classifier>
</dependency>
<dependency>
<groupId>com.my.stuff</groupId>
<artifactId>my-stuff</artifactId>
<version>${my-stuff.version}</version>
</dependency>
</dependencies>

`'dependencies.dependency.version'` is missing in multi module inherited project though we use <dependencymanagement>

I have a common dependency that needs to be used across different poms.Here for ex spring-ws-core is what I need to use on Pom A, Pom B etc .Pom A will inherit properly but when I remove the version in Pom B it is throwing issue.
Common
<dependency>
<groupId>org.springframework.ws</groupId>
<artifactId>spring-ws-core</artifactId>
<version>5.0 RELEASE</version>
</dependency>
Pom A
<dependecyManagement>
<dependencies>
<dependency>
<groupId>Common</groupId>
<artifactId>Common</artifactId>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependecyManagement>
<dependencies>
Note:I am not using version since it is inheriting from
<dependencymangement > centralized pom
<dependency>
<groupId>org.springframework.ws</groupId>
<artifactId>spring-ws-core</artifactId>
<dependency>
</dependencies>
Pom B:
**Parent will be Pom A **
<parent>
<groupId>Pom A</groupId>
<artifactId>Pom A</artifactId>
<version>someversion</version>
<relativePath>pom A.xml</relativePath>
</parent>
This doesn't have <dependencymanagement> since it should be inherited from Pom A since Pom A has <dependecymanagement>
Now my issue if I add any dependency without version in Pom B it is throwing 'dependencies.dependency.version' is missing.How to inherit to Pom B from common is what I am looking for .If I add <dependencymanagement> in Pom B it is not working as expected .
Anyone can shed some light would be appreciated.

Maven Dependency Version As Property

I have a maven pom file that defines a dependency as such:
<dependencies>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.6</version>
</dependency>
</dependencies>
It is often said that everything in the pom can be referenced as a Maven property:
https://bowerstudios.com/node/991
For example, you can read ${project.version}, ${project.build}, etc. Is there a way to read a dependency's version as a Maven property, ala ${project.dependencies.dependency.groupId=org.apache.httpcomponents&artifactId=httpclient.version} ?

You could define a custom property under <properties> and refer to it from your dependency. Preferred way is to place the property in parent pom (if exist and is a multi module project). Alternately, you can skip the <version> altogether if you had defined the <dependency> in <dependency-management> section
<properties>
<http.client.version>4.3.6</http.client.version>
</properties>
...
<dependencies>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>${http.client.version}</version>
</dependency>
</dependencies>

Maven - moved code to new artifact; transitive dependencies issue

Here is my situation:
I created a new artifact in a library called 'web-ng-framework', and moved code into it from an old artifact in the library, 'web'
I deleted the 'web' artifact
And here is the problem:
ProjectA uses an older version of the library, and so it has a compile dependency on 'web'
ProjectB depends on ProjectA
ProjectB uses the latest version of the library, so when ProjectB is built, it contains both the 'web' and 'web-ng-framework' libraries, causing a possible conflict
Does anyone know how I can solve this? Thanks!
EDIT:
Would doing 'relocation' of 'web' to 'web-ng-framework' maybe work better? In ProjectA, I could include a dependency on 'web' so that Maven would see that what it really needs is 'web-ng-framework'. Would that work?

When including ProjectA in ProjectB exclude web. Like this
<dependency>
<groupId>your.group</groupId>
<artifactId>projectA</artifactId>
<exclusions>
<exclusion>
<groupId>your.group</groupId>
<artifactId>web</artifactId>
</exclusion>
</exclusions>
</dependency>

A classic solution to this problem is the 'Version 99' hack.
To do this, use the following in your root pom:
<dependencyManagement>
<dependency>
<groupId>your.group</groupId>
<artifactId>web</artifactId>
<version>99.0-does-not-exist</version>
</dependency>
</dependencyManagement>
Then put an empty web-99.0-does-not-exist.pom and web-99.0-does-not-exist.jar in your repository.
This ensures that every project that inherits from this root pom will not get the old version of the web.jar anymore.

I suggest that you use optional dependencies
This can be acheived by making web depencency optional in projectA.
<project>
<groupId>some.group</groupId>
<artifactId>projectA</artifactId>
...
<dependencies>
<!-- declare the dependency to be set as optional -->
<dependency>
<groupId>some.group</groupId>
<artifactId>web</artifactId>
<version>1.0</version>
<scope>compile</scope>
<optional>true</optional>
</dependency>
</dependencies>
</project>
When declaring some other project that depends on projectA the web dependency will not be included.
<project>
<groupId>some.group</groupId>
<artifactId>projectB</artifactId>
...
<dependencies>
<dependency>
<groupId>some.group</groupId>
<artifactId>projectA</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>some.group</groupId>
<artifactId>web-ng-framework</artifactId>
<version>1.0</version>
</dependency>
</dependencies>
</project>
Now projectB will only have a dependency on projectA and web-ng-framework, not web.