When the Tool parameter is an empty string, a type conversion error occurs, reporting java.lang.NumberFormatException

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Bug description
A clear and concise description of what the bug is about.

A type conversion error occurs when the Tool parameter is an empty string, throwing java.lang.NumberFormatException.

• The parameter type of the tool is Long.
• The Tool parameter responded by the LLM is an empty string.

java.lang.NumberFormatException
	at java.base/java.math.BigDecimal.<init>([BigDecimal.java:692](http://bigdecimal.java:692/))
	at java.base/java.math.BigDecimal.<init>([BigDecimal.java:471](http://bigdecimal.java:471/))
	at java.base/java.math.BigDecimal.<init>([BigDecimal.java:900](http://bigdecimal.java:900/))
	at [org.springframework.ai](http://org.springframework.ai/).util.json.JsonParser.toTypedObject([JsonParser.java:139](http://jsonparser.java:139/))
	at [org.springframework.ai](http://org.springframework.ai/).tool.method.MethodToolCallback.buildTypedArgument([MethodToolCallback.java:150](http://methodtoolcallback.java:150/))
	at [org.springframework.ai](http://org.springframework.ai/).tool.method.MethodToolCallback.lambda$buildMethodArguments$1([MethodToolCallback.java:139](http://methodtoolcallback.java:139/))
	at java.base/[java.util.stream](http://java.util.stream/).ReferencePipeline$3$1.accept([ReferencePipeline.java:197](http://referencepipeline.java:197/))
	at java.base/java.util.Spliterators$ArraySpliterator.forEachRemaining([Spliterators.java:992](http://spliterators.java:992/))
	at java.base/[java.util.stream](http://java.util.stream/).AbstractPipeline.copyInto([AbstractPipeline.java:509](http://abstractpipeline.java:509/))
	at java.base/[java.util.stream](http://java.util.stream/).AbstractPipeline.wrapAndCopyInto([AbstractPipeline.java:499](http://abstractpipeline.java:499/))
	at java.base/[java.util.stream](http://java.util.stream/).AbstractPipeline.evaluate([AbstractPipeline.java:575](http://abstractpipeline.java:575/))
	at java.base/[java.util.stream](http://java.util.stream/).AbstractPipeline.evaluateToArrayNode([AbstractPipeline.java:260](http://abstractpipeline.java:260/))
	at java.base/[java.util.stream](http://java.util.stream/).ReferencePipeline.toArray([ReferencePipeline.java:616](http://referencepipeline.java:616/))
	at java.base/[java.util.stream](http://java.util.stream/).ReferencePipeline.toArray([ReferencePipeline.java:622](http://referencepipeline.java:622/))
	at [org.springframework.ai](http://org.springframework.ai/).tool.method.MethodToolCallback.buildMethodArguments([MethodToolCallback.java:140](http://methodtoolcallback.java:140/))
	at [org.springframework.ai.tool.method.MethodToolCallback.call](http://org.springframework.ai.tool.method.methodtoolcallback.call/)([MethodToolCallback.java:107](http://methodtoolcallback.java:107/))

Environment
Please provide as many details as possible: Spring AI version, Java version, which vector store you use if any, etc

• Spring AI 1.0.0

Steps to reproduce
Steps to reproduce the issue.

Expected behavior
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Should an empty string be converted to null? Of course, that's a matter for discussion.

Minimal Complete Reproducible example
Please provide a failing test or a minimal complete verifiable example that reproduces the issue.
Bug reports that are reproducible will take priority in resolution over reports that are not reproducible.

Start by reading org.springframework.ai.util.json.JsonParser.toTypedObject at JsonParser.java:139 and the argument conversion flow in MethodToolCallback.java:107-150. Reproduce the empty-string Tool parameter with a Long type if possible, then establish and verify the agreed behavior for that input without the NumberFormatException.