ERROR:java.lang.NullPointerException: Cannot invoke "com.fasterxml.jackson.databind.JsonNode.getNodeType()" because the return value of "com.fasterxml.jackson.databind.JsonNode.get(String)" is null

I used with langchain4j with java, however, occured the ERROR
@Bean
public McpClient firecrawlMcpClient() {
List command = List.of(
"firecrawl-mcp" // 或者用完整路径，避免依赖 npx
);

Map environment = Map.of(
"FIRECRAWL_API_KEY", firecrawlApiKey
);

return McpClientFactory.createMcpClient(command, environment);
}

java.lang.NullPointerException: Cannot invoke "com.fasterxml.jackson.databind.JsonNode.getNodeType()" because the return value of "com.fasterxml.jackson.databind.JsonNode.get(String)" is null
at dev.langchain4j.mcp.client.ToolSpecificationHelper.jsonNodeToJsonSchemaElement(ToolSpecificationHelper.java:48) ~[langchain4j-mcp-1.0.0-beta3.jar:na]
at dev.langchain4j.mcp.client.ToolSpecificationHelper.jsonNodeToJsonSchemaElement(ToolSpecificationHelper.java:68) ~[langchain4j-mcp-1.0.0-beta3.jar:na]
at dev.langchain4j.mcp.client.ToolSpecificationHelper.toolSpecificationListFromMcpResponse(ToolSpecificationHelper.java:37) ~[langchain4j-mcp-1.0.0-beta3.jar:na]
at dev.langchain4j.mcp.client.DefaultMcpClient.obtainToolList(DefaultMcpClient.java:266) ~[langchain4j-mcp-1.0.0-beta3.jar:na]
at dev.langchain4j.mcp.client.DefaultMcpClient.listTools(DefaultMcpClient.java:139) ~[langchain4j-mcp-1.0.0-beta3.jar:na]
at dev.langchain4j.mcp.McpToolProvider.provideTools(McpToolProvider.java:34) ~[langchain4j-mcp-1.0.0-beta3.jar:na]
at

Start with dev.langchain4j.mcp.client.ToolSpecificationHelper.java at line 48 and trace the tool-list response returned by the firecrawl-mcp command. Check which MCP schema field is missing before the JsonNode access; done means the reported tool discovery path no longer throws this NullPointerException for the shown integration.

Written by the indexing model from the issue text.