chore(deps): bump org.apache.hadoop:hadoop-common from 3.2.4 to 3.4.0 in /other/java/hdfs3 (#7512)

* chore(deps): bump org.apache.hadoop:hadoop-common in /other/java/hdfs3

Bumps org.apache.hadoop:hadoop-common from 3.2.4 to 3.4.0.

---
updated-dependencies:
- dependency-name: org.apache.hadoop:hadoop-common
  dependency-version: 3.4.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

* add java client unit tests

* Update dependency-reduced-pom.xml

* add java integration tests

* fix

* fix buffer

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: chrislu <chris.lu@gmail.com>

1 files changed, 190 insertions, 0 deletions

diff --git a/other/java/hdfs2/README.md b/other/java/hdfs2/README.md
new file mode 100644
index 000000000..e98b06506
--- /dev/null
+++ b/other/java/hdfs2/README.md
@@ -0,0 +1,190 @@
+# SeaweedFS Hadoop2 Client
+
+Hadoop FileSystem implementation for SeaweedFS, compatible with Hadoop 2.x/3.x.
+
+## Building
+
+```bash
+mvn clean install
+```
+
+## Testing
+
+This project includes two types of tests:
+
+### 1. Configuration Tests (No SeaweedFS Required)
+
+These tests verify configuration handling and initialization logic without requiring a running SeaweedFS instance:
+
+```bash
+mvn test -Dtest=SeaweedFileSystemConfigTest
+```
+
+### 2. Integration Tests (Requires SeaweedFS)
+
+These tests verify actual FileSystem operations against a running SeaweedFS instance.
+
+#### Prerequisites
+
+1. Start SeaweedFS with default ports:
+   ```bash
+   # Terminal 1: Start master
+   weed master
+   
+   # Terminal 2: Start volume server
+   weed volume -mserver=localhost:9333
+   
+   # Terminal 3: Start filer
+   weed filer -master=localhost:9333
+   ```
+
+2. Verify services are running:
+   - Master: http://localhost:9333
+   - Filer HTTP: http://localhost:8888
+   - Filer gRPC: localhost:18888
+
+#### Running Integration Tests
+
+```bash
+# Enable integration tests
+export SEAWEEDFS_TEST_ENABLED=true
+
+# Run all tests
+mvn test
+
+# Run specific test
+mvn test -Dtest=SeaweedFileSystemTest
+```
+
+### Test Configuration
+
+Integration tests can be configured via environment variables or system properties:
+
+- `SEAWEEDFS_TEST_ENABLED`: Set to `true` to enable integration tests (default: false)
+- Tests use these default connection settings:
+  - Filer Host: localhost
+  - Filer HTTP Port: 8888
+  - Filer gRPC Port: 18888
+
+### Running Tests with Custom Configuration
+
+To test against a different SeaweedFS instance, modify the test code or use Hadoop configuration:
+
+```java
+conf.set("fs.seaweed.filer.host", "your-host");
+conf.setInt("fs.seaweed.filer.port", 8888);
+conf.setInt("fs.seaweed.filer.port.grpc", 18888);
+```
+
+## Test Coverage
+
+The test suite covers:
+
+- **Configuration & Initialization**
+  - URI parsing and configuration
+  - Default values
+  - Configuration overrides
+  - Working directory management
+
+- **File Operations**
+  - Create files
+  - Read files
+  - Write files
+  - Append to files
+  - Delete files
+
+- **Directory Operations**
+  - Create directories
+  - List directory contents
+  - Delete directories (recursive and non-recursive)
+
+- **Metadata Operations**
+  - Get file status
+  - Set permissions
+  - Set owner/group
+  - Rename files and directories
+
+## Usage in Hadoop
+
+1. Copy the built JAR to your Hadoop classpath:
+   ```bash
+   cp target/seaweedfs-hadoop2-client-*.jar $HADOOP_HOME/share/hadoop/common/lib/
+   ```
+
+2. Configure `core-site.xml`:
+   ```xml
+   <configuration>
+     <property>
+       <name>fs.seaweedfs.impl</name>
+       <value>seaweed.hdfs.SeaweedFileSystem</value>
+     </property>
+     <property>
+       <name>fs.seaweed.filer.host</name>
+       <value>localhost</value>
+     </property>
+     <property>
+       <name>fs.seaweed.filer.port</name>
+       <value>8888</value>
+     </property>
+     <property>
+       <name>fs.seaweed.filer.port.grpc</name>
+       <value>18888</value>
+     </property>
+   </configuration>
+   ```
+
+3. Use SeaweedFS with Hadoop commands:
+   ```bash
+   hadoop fs -ls seaweedfs://localhost:8888/
+   hadoop fs -mkdir seaweedfs://localhost:8888/test
+   hadoop fs -put local.txt seaweedfs://localhost:8888/test/
+   ```
+
+## Continuous Integration
+
+For CI environments, tests can be run in two modes:
+
+1. **Configuration Tests Only** (default, no SeaweedFS required):
+   ```bash
+   mvn test -Dtest=SeaweedFileSystemConfigTest
+   ```
+
+2. **Full Integration Tests** (requires SeaweedFS):
+   ```bash
+   # Start SeaweedFS in CI environment
+   # Then run:
+   export SEAWEEDFS_TEST_ENABLED=true
+   mvn test
+   ```
+
+## Troubleshooting
+
+### Tests are skipped
+
+If you see "Skipping test - SEAWEEDFS_TEST_ENABLED not set":
+```bash
+export SEAWEEDFS_TEST_ENABLED=true
+```
+
+### Connection refused errors
+
+Ensure SeaweedFS is running and accessible:
+```bash
+curl http://localhost:8888/
+```
+
+### gRPC errors
+
+Verify the gRPC port is accessible:
+```bash
+# Should show the port is listening
+netstat -an | grep 18888
+```
+
+## Contributing
+
+When adding new features, please include:
+1. Configuration tests (no SeaweedFS required)
+2. Integration tests (with SEAWEEDFS_TEST_ENABLED guard)
+3. Documentation updates
+