General issue with setup

Hello,
I am currently walking through setting up CodeQL. For simplicity I am using the java example and query from this [link](https://codeql.github.com/docs/codeql-language-guides/basic-query-for-java-code/).

```
public class TestJava {
void myJavaFun(String s) {
boolean b = s.equals("");
}
}
```
```
from MethodAccess ma
where
ma.getMethod().hasName("equals") and
ma.getArgument(0).(StringLiteral).getValue() = ""
select ma, "This comparison to empty string is inefficient, use isEmpty() instead."
```
Just so that I can get my environment setup. In addition, I am using Maven and VSCode. I have both the VSCode extension and the CLI installed. However, I am running into a few issues.

1) The first is getting the database created. I am first building with Maven to get the .class files. After that I am creating a database from these files. I tried doing these two steps in sperate commands,

```
mvn clean
codeql database create codeql_project --command="mvn install --file ../../../pom.xml" --language=java --overwrite --source-root=target/classes/snippets/
```
However, this causes this error
> CodeQL detected code written in , but not any written in Java/Kotlin. This can occur if the specified build commands failed to compile or process any code.
> - Confirm that there is some source code for the specified language in the project.
> - For codebases written in Go, JavaScript, TypeScript, and Python, do not specify
an explicit --command.
> - For other languages, the --command must specify a "clean" build which compiles
all the source code files without reusing existing build artefacts.
It seems like Java falls in the "Other" category.

Due to this, I am trying both steps in one command.
```
codeql database create codeql_project --command="mvn clean install --file ../../../pom.xml" --language=java --overwrite --source-root=target/classes/snippets/
```
The issue with this is that Maven will delete the target dir during the clean phase, which then causes issues with the source-root.

Currently, the only way I have been able to get a working database is by not specifiying the source-root with this command.
```
codeql database create codeql_project --language=java --command="mvn clean install --file pom.xml"
```
However, I don't feel confident that this is correctly working.

2) In addition I am getting a lot of type errors. Circling back to using the query above. I am getting
> Failed to run query: ERROR: Could not resolve type MethodAccess (C:\Users\Kyler-Laptop\Downloads\Demo1\Demo\codeql_queries\SimpleQuery.ql:1,6-18)
ERROR: Could not resolve type StringLiteral (C:\Users\Kyler-Laptop\Downloads\Demo1\Demo\codeql_queries\SimpleQuery.ql:4,22-35)

This is what originally made me think my database create command might be incorrect.

Any suggestions would be greatly appreciated.
Thank you