adding strategy serialization optimization

[RanVaknin]

This PR addresses a performance degradation issue between v1 and v2. After considering multiple implementation approaches, the proposed optimization approach yielded roughly 10% reduction in latency from the v1 performance.

toJson() Benchmarks

Metrics	p0.90	p0.95	p0.99	Change (p90)
v1	611µs	634µs	739µs	baseline
v2 Current	2,953µs	2,527µs	2,404µs	+383%
v2 SDKJsonGenerator - writes to byteArrayOutputStream (enum based dispatch)	550µs	564µs	613µs	- 10%
v2 JsonGenerator - writes to stringWriter (enum based dispatch)	680µs	719µs	1541µs	+11%
v2 SDKJsonGenerator (static method dispatch)	918µs	935µs	1,118µs	+50%

getJson() Benchmarks

2KB payload

Metrics	p0.50	p0.90	p0.99	Change (p90)
v1	1.780µs	1.834µs	2.332µs	baseline
v2 Current	8.640µs	9.360µs	11.248µs	+410%
v2 Optimized	2.231µs	2.332µs	2.872µs	+27%

50KB payload

Metrics	p0.50	p0.90	p0.99	Change (p90)
v1	593µs	610µs	699µs	baseline
v2 Current	2,442µs	2,744µs	3,498µs	+350%
v2 Optimized	548µs	572µs	690µs	-6%

Key Design Decisions

1. Enum based dispatch outperforms static methods through JIT optimization

When the JVM encounters the enum approach, it sees strategy.serialize(generator, av) calls where each enum constant (STRING, NUMBER, etc.) is a singleton instance. The JIT compiler recognizes these as monomorphic call sites - meaning each location in the code consistently calls the same concrete method.

// Enum approach - JIT sees monomorphic call sites
JsonSerializationStrategy strategy = getStrategy(av);
strategy.serialize(generator, av); // Inlines to direct method call

In contrast, the static method approach forces all serialization logic through a single serializeAttributeValue() method containing if-else branches. While the JIT can optimize the branching logic, it cannot eliminate the method call itself or the internal conditional overhead.

// Static approach - retains method call overhead
serializeAttributeValue(generator, av); // Must evaluate all conditions

The JFR data confirms that the enum implementation approach generated 1,333 Jackson Generator method calls compared to 2,159 in the static approach.

2. SdkJsonGenerator (ByteArrayOutputStream) over JsonGenerator (StringWriter)

Tested both serialization approaches with identical enum dispatch logic:
• SdkJsonGenerator wraps JsonFactory.createGenerator(ByteArrayOutputStream) → creates UTF8JsonGenerator - 19% faster (550µs vs 680µs at p90)
• JsonGenerator with JsonFactory.createGenerator(StringWriter) → creates WriterBasedJsonGenerator

⚠️ Potential behavior change

UTF8JsonGenerator escapes non ASCII as \uXXXX by default. Jackson 2.18+ provides COMBINE_UNICODE_SURROGATES_IN_UTF8 feature to output literal UTF-8 (verified via test), but the SDK bundles older shaded Jackson version that lacks this feature.
see FasterXML/jackson-core#223

[sonarqubecloud]

Quality Gate passed

Issues
61 New issues
0 Accepted issues

Measures
0 Security Hotspots
88.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud