Addressing the NPE risk in AnthropicChatModel#getDefaultUsage

When either `usage.inputTokens` or `usage.outputTokens()` is null, `usage.inputTokens() + usage.outputTokens()` will throw an NPE.

Signed-off-by: Forte Scarlet <[email protected]>
Signed-off-by: logan-mac <[email protected]>

Author: ForteScarlet

models/spring-ai-anthropic/src/main/java/org/springframework/ai/anthropic/AnthropicChatModel.java

@@ -229,8 +229,9 @@ public ChatResponse internalCall(Prompt prompt, ChatResponse previousChatRespons
 	}
 
 	private DefaultUsage getDefaultUsage(AnthropicApi.Usage usage) {
-		return new DefaultUsage(usage.inputTokens(), usage.outputTokens(), usage.inputTokens() + usage.outputTokens(),
-				usage);
+		Integer inputTokens = usage.inputTokens() != null ? usage.inputTokens() : 0;
+		Integer outputTokens = usage.outputTokens() != null ? usage.outputTokens() : 0;
+		return new DefaultUsage(inputTokens, outputTokens, inputTokens + outputTokens, usage);
 	}
 
 	@Override