ADDITIONAL SYSTEM INFORMATION :
macOS x64
openjdk version "21.0.1" 2023-10-17
OpenJDK Runtime Environment (build 21.0.1+12-29)
OpenJDK 64-Bit Server VM (build 21.0.1+12-29, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
I am using string template processor to convert a sql into a prepared statement.  
I made some encapsulation to form a nice dsl, the code looks like this:

```
jdbc.transaction(conn -> {
    var name = "a";
    var age = 100;
    conn.prepare()."""
        insert into "test_user" ("name", "age") values (\{name}, \{age})"""
        .execute();
});
```

The error occurred here: "conn.prepare(". The javac says: "processor type cannot be a raw type"

There are two overloading methods with name `transaction`:  
```
void transaction(Consumer<ConnectionW> f);
<T> T transaction(Function<ConnectionW, T> f);
```

Here are the workarounds I've tried.

1. javac compiles without any problem if I remove the second overloading method.
2. javac also compiles if I change "jdbc.transaction(conn ->" into "jdbc.transaction((ConnectionW conn) ->"
3. javac also compiles if I change "jdbc.transaction(conn ->" into "jdbc.transaction((Consumer<ConnectionW>) conn ->"
4. javac also compiles if I add a standalone variable "SQL sql = conn.prepare()" and then `sql."xxx"`
5. But javac won't compile if I use "var sql = conn.prepare()" and then `sql."xxx"`

Detailed information including a reproducing code snippet can be found below.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
The buggy code:

Bad00Main.java

```
import java.util.function.*;

class JDBC {
  void transaction(Consumer<ConnectionW> f) {
    f.accept(new ConnectionW());
  }
  <T> T transaction(Function<ConnectionW, T> f) {
    return f.apply(new ConnectionW());
  }
}

class ConnectionW {
  SQL prepare() {
    return new SQL();
  }
}

class SQL implements StringTemplate.Processor<PreparedStatementW, RuntimeException> {
  public PreparedStatementW process(StringTemplate template) throws RuntimeException {
    System.out.println(template.fragments());
    return new PreparedStatementW();
  }
}

class PreparedStatementW {
  void execute() {
    System.out.println("Here I am!");
  }
}

void main() {
  var jdbc = new JDBC();
  jdbc.transaction(conn -> {
    var name = "a";
    var age = 100;
    conn.prepare()."""
      insert into "test_user" ("name", "age") values (\{name}, \{age})"""
      .execute();
  });
}
```

Javac command:

```
javac --source 21 --enable-preview Bad00Main.java
```

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The code compiles without any problem, and print the following lines when executed:

```
[insert into "test_user" ("name", "age") values (, , , )]
Here I am!
```
ACTUAL -
Picked up JAVA_TOOL_OPTIONS: -Duser.language=en
Bad00Main.java:36: error: processor type cannot be a raw type: prepare
    conn.prepare()."""
                ^
Note: Bad00Main.java uses preview features of Java SE 21.
Note: Recompile with -Xlint:preview for details.
1 error

---------- BEGIN SOURCE ----------
https://gist.github.com/wkgcass/6388da63eb1ea858e21717171d8efa68

Bad00Main is the code represented in this post.

OK01~04Main and Bad05Main corresponds to 1~5 described in the "Description" section in this post.
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
1~4 described in the "Description" section in this post.

FREQUENCY : always