`FilterExpressionTextParser` shares mutable error state across instances

Start with FilterExpressionTextParser, its constructor, parse() flow, and DescriptiveErrorListener.INSTANCE usage. Use the provided JUnit regression test as the first check, then verify that separate parser instances collect diagnostics independently during concurrent invalid parses.

Bug description

FilterExpressionTextParser assigns the same mutable DescriptiveErrorListener.INSTANCE to every parser instance.

Each call to parse() clears, modifies, and reads the listener's shared errorMessages list. Concurrent parsing through separate parser instances can therefore interfere with diagnostic collection performed by another invocation.

CopyOnWriteArrayList makes individual list operations thread-safe, but it does not isolate the compound clear → parse → join sequence.

If the maintainers agree that this is a bug, I would be happy to work on the fix and submit a pull request with regression tests.

Environment

• Spring AI: 2.0.1-SNAPSHOT
• Tested artifact: spring-ai-vector-store-2.0.1-20260808.133500-105.jar
• Java: 17.0.17
• ANTLR runtime: 4.13.2
• Vector store: none required

Steps to reproduce

1. Create two separate FilterExpressionTextParser instances.
2. Retrieve the errorListener assigned to each instance.
3. Observe that both parser instances use the same listener.
4. Run invalid parse operations concurrently and observe that both calls operate
   on the same errorMessages collection.

Relevant implementation:

public FilterExpressionTextParser(ANTLRErrorStrategy handler) {
      this.errorListener = DescriptiveErrorListener.INSTANCE;
      this.errorHandler = handler;
}

parser.removeErrorListeners();
this.errorListener.errorMessages.clear();
parser.addErrorListener(this.errorListener);

var msg = String.join("", this.errorListener.errorMessages);

Expected behavior

Each parser invocation, or at least each parser instance, should collect its syntax error messages independently. Concurrent parsing should not clear or modify diagnostics belonging to another invocation.

Minimal Complete Reproducible example

The following JUnit test fails because both parser instances receive the same
mutable error listener:

import java.lang.reflect.Field;

import org.junit.jupiter.api.Test;

import org.springframework.ai.vectorstore.filter.FilterExpressionTextParser;

import static org.assertj.core.api.Assertions.assertThat;

class FilterExpressionTextParserConcurrencyTests {

      @Test
      void parserInstancesShouldNotShareMutableErrorListener() throws Exception {
              var firstParser = new FilterExpressionTextParser();
              var secondParser = new FilterExpressionTextParser();

              Field listenerField =
                              FilterExpressionTextParser.class.getDeclaredField("errorListener");
              listenerField.setAccessible(true);

              Object firstListener = listenerField.get(firstParser);
              Object secondListener = listenerField.get(secondParser);

              assertThat(firstListener).isNotSameAs(secondListener);
      }

}

Actual result:

Expecting actual:
  org.springframework.ai.vectorstore.filter.FilterExpressionTextParser$DescriptiveErrorListener@...
not to be the same as:
  org.springframework.ai.vectorstore.filter.FilterExpressionTextParser$DescriptiveErrorListener@...