Invalid Automatic-Module-Name in mcp-core

[cdivilly]

Fixes #560

• Uses build-helper-maven-plugin to generate a Maven property named automatic.module.name generated from ${project.groupId}.${project.artifactId}, whilst ensuring the value is a syntactically valid Java Module name, by replacing any - characters with . characters
• Remove legacy configuration of Automatic-Module-Name in ./mcp-core/pom.xml bnd-maven-plugin configuration which was generating a value with an invalid value (Java Module names cannot contain the - character)
• Modifies ./pom.xml maven-jar-plugin configuration to add Automatic-Module-Name property to the JAR manifest. Doing this here, ensures each sub-project JAR has a valid automatic module name

Motivation and Context

In versions 0.12.1 and older, the SDK consisted of a single module, mcp. The Automatic-Module-Name manifest attribute was generated by the bnd-maven-plugin. Note that the single module name does not contain any dash (-) characters.

In 0.13.0 and later, the SDK was refactored into multiple modules, mcp-core, mcp-json etc. Note the addition of the - character in the artifactId. The existing logic for generating Automatic-Module-Name was not updated, resulting in syntactically invalid values being generated for the value, as Java module names are not allowed contain the - character:

Automatic-Module-Name: io.modelcontextprotocol.sdk.mcp-core

• This invalid module name prevents use of 0.13.0 and later versions of the SDK in any Java application that uses Java Modules.

With the changes described above, this becomes:

Automatic-Module-Name: io.modelcontextprotocol.sdk.mcp.core

• Java module based applications can once again use the MCP SDK

How Has This Been Tested?

• Checked the contents of META/MANIFEST.MF in each jar is a valid Java module name
• Rebuilt the downstream application that was regressed by this issue using the rebuilt jars. Compile time error previously reported no longer occurs

Breaking Changes

• OSGi support is explicitly removed, but OSGi has been broken since 0.13.0 anyways, so effectively this PR does not change the status of OSGi support.
• I have a branch that could restore OSGi support: main...cdivilly:mcp-java-sdk:fix/mcp-osgi-support. I am unhappy with the approach taken, I think a more comprehensive solution would build OSGi support into each module. I'm unconvinced this repo should take on that effort.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

• One new maven plugin: org.codehaus.mojo:build-helper-maven-plugin is added to the root pom.xml. This purpose of this plugin is to generate and rewrite the value of ${automatic.module.name} property into a syntactically valid Java module name
• Configuring Automatic-Module-Name is moved from the bnd-maven-plugin configuration to the maven-jar-plugin configuration, so it can be uniformly applied to all sub-modules.

[cdivilly]

More testing shows a split package issue. The package io.modelcontextprotocol.json is duplicated across the mcp-core and mcp-json jars. The package does not appear in the source code for mcp-core, it appears to be added in during the build process.

In Java modules, it is not permitted for the same package name to be used in more than one jar.

[cdivilly]

The bnd-maven-plugin is pulling in the io.modelcontextprotocol.json package into mcp-core/target/classes

Due to the specific bnd-maven-plugin configuration in mcp-core, the class files from mcp-json are assembled into the mcp-core jar.

[cdivilly]

I've revised this PR to address the split package issue.

1. Move automatic module name generation to maven-jar-plugin. Ensures all modules have a valid name
2. Remove OSGi config from mcp-core. bnd-maven-plugin causes the classes in mcp-json to be duplicated into mcp-core, which then causes split-package issue.
3. I've prepared a separate branch that would restore the OSGi support, but I am not in favour of merging it as it leads to a bifurcated dependency graph. The branch is here: main...cdivilly:mcp-java-sdk:fix/mcp-osgi-support