execute empty sql causing IndexOutOfBoundsException

[trung]

Bug Report

Versions

• Driver: io.r2dbc.h2
• Database: H2
• Java: 17
• OS: MacOS

Current Behavior

Stack trace

Caused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0
	at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) ~[na:na]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Assembly trace from producer [reactor.core.publisher.FluxIterable] :
	reactor.core.publisher.Flux.fromIterable(Flux.java:1117)
	io.r2dbc.h2.H2Statement.execute(H2Statement.java:140)
Error has been observed at the following site(s):
	*_______________________Flux.fromIterable ⇢ at io.r2dbc.h2.H2Statement.execute(H2Statement.java:140)
	|_                               Flux.map ⇢ at io.r2dbc.h2.H2Statement.execute(H2Statement.java:141)
	*____________________________Flux.flatMap ⇢ at io.r2dbc.h2.H2Statement.execute(H2Statement.java:105)
	|_                              Flux.cast ⇢ at org.springframework.r2dbc.core.ResultFunction.apply(ResultFunction.java:66)
	|_                             checkpoint ⇢ SQL ..<snip>..

Table schema

Input Code

insert xyz; \n

Steps to reproduce

This unit test doesn't produce the IndexOutOfBoundsException but to demonstrate that empty sql is allowed to execute.
This creates a root issue in the SessionClient.createCommand().

Input Code

@Test
void executeMultipleCommandsIgnoringEmptyOne() {
    CommandInterface insertCommand1 = mock(CommandInterface.class);
    when(this.client.prepareCommand("insert test-query-1", Collections.emptyList())).thenReturn(Collections.singleton(insertCommand1).iterator());
    when(this.client.update(insertCommand1, false)).thenReturn(new ResultWithGeneratedKeys.WithKeys(0, new LocalResult()));

    new H2Statement(this.client, this.codecs, "insert test-query-1;\n  ")
        .execute()
        .as(StepVerifier::create)
        .expectNextCount(1)
        .verifyComplete();
}

Expected behavior/code

Empty SQL should be filtered

Possible Solution

N/A

Additional context

When using Spring Data and """-quoted string query as below:

@Query("""
insert test-query-1;
""")
Mono<Void> insert();