Sure, here’s a Java Maven project structure that includes the implementation of a `solution` function which multiplies two integers, along with test cases for this function.

### **pom.xml**
```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.example</groupId>
    <artifactId>solution</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>
```

### **src/main/java/com/example/solution/Solution.java**
```java
package com.example.solution;

public class Solution {
    public int solution(int a, int b) {
        return a * b;
    }
}
```

### **src/test/java/com/example/solution/SolutionTest.java**
```java
package com.example.solution;

import static org.junit.Assert.assertEquals;
import org.junit.Test;

public class SolutionTest {
    @Test
    public void testSolution() {
        Solution sol = new Solution();
        assertEquals(0, sol.solution(0, 5));
        assertEquals(-10, sol.solution(2, -5));
        assertEquals(10, sol.solution(2, 5));
        assertEquals(49, sol.solution(7, 7));
    }
}
```

### **Compile**
```bash
# Compile the code
mvn compile
```

### **Test**
```bash
# Run the tests
mvn test
```

This setup uses Maven to handle dependencies and build configurations. The provided commands will compile the code and run the specified tests, ensuring your function works as expected across different scenarios.