UserMessage is also excluded in requests with IncludeContents.NONE

[nlinhvu]

Describe the bug
As the doc

adk-java/core/src/main/java/com/google/adk/agents/LlmAgent.java

Lines 76 to 79 in cca154d

	/**
	* Enum to define if contents of previous events should be included in requests to the underlying
	* LLM.
	*/

With this

LlmAgent.builder()
    .includeContents(LlmAgent.IncludeContents.NONE)

I expect the current user message (event) should be sent. Do I understand it correct?

It looks like all contents (include the current user message) being deleted at the current version:

adk-java/core/src/main/java/com/google/adk/flows/llmflows/Contents.java

Lines 56 to 60 in cca154d

	if (llmAgent.includeContents() == LlmAgent.IncludeContents.NONE) {
	return Single.just(
	RequestProcessor.RequestProcessingResult.create(
	request.toBuilder().contents(ImmutableList.of()).build(), ImmutableList.of()));
	}

[Poggecci]

Thanks for reporting this, solving in #334!