Add backwards compatibility constructors and tests (#395)

- Updated integration tests to include assertions for `meta` being
`null` in the `listTools`, `listResources`, `readResource`, and
`callTool` results.
- Renamed test cases in `SseServerIntegrationTest` for clarity.
- Added (deprecated) synthetic constructors for various request
parameter classes.
- Enhanced naming conventions and structure in integration test cases.
- Replaced `throw Error(...)` with `error(...)` for cleaner error
handling.

## Motivation and Context
To verify backwards-compatibility after schema change

## How Has This Been Tested?
CI, integration tests, regression tests (samples)

## Breaking Changes
<!-- Will users need to update their code or configurations? -->

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
- [x] Test update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

kotlin-sdk-test/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/integration/kotlin/OldSchemaAbstractResourceIntegrationTest.kt

@@ -16,6 +16,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.test.runTest
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertNull
 import org.junit.jupiter.api.assertThrows
 import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.test.Ignore
@@ -145,6 +146,7 @@ abstract class OldSchemaAbstractResourceIntegrationTest : OldSchemaKotlinTestBas
         val result = client.listResources()
 
         assertNotNull(result, "List resources result should not be null")
+        assertNull(actual = result.meta, "List resources meta should be null")
         assertTrue(result.resources.isNotEmpty(), "Resources list should not be empty")
 
         val testResource = result.resources.find { it.uri == testResourceUri }
@@ -158,6 +160,7 @@ abstract class OldSchemaAbstractResourceIntegrationTest : OldSchemaKotlinTestBas
         val result = client.readResource(ReadResourceRequest(ReadResourceRequestParams(uri = testResourceUri)))
 
         assertNotNull(result, "Read resource result should not be null")
+        assertNull(actual = result.meta, "Read resource result meta should be null")
         assertTrue(result.contents.isNotEmpty(), "Resource contents should not be empty")
 
         val content = result.contents.firstOrNull() as? TextResourceContents

kotlin-sdk-test/src/jvmTest/kotlin/io/modelcontextprotocol/kotlin/sdk/integration/kotlin/OldSchemaAbstractToolIntegrationTest.kt

@@ -21,6 +21,7 @@ import kotlinx.serialization.json.buildJsonArray
 import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.put
 import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.assertNull
 import java.text.DecimalFormat
 import java.text.DecimalFormatSymbols
 import java.util.Locale
@@ -431,7 +432,8 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
     fun testListTools(): Unit = runBlocking(Dispatchers.IO) {
         val result = client.listTools()
 
-        assertNotNull(result, "List utils result should not be null")
+        assertNotNull(result, "List tools result should not be null")
+        assertNull(actual = result.meta, "List tools result meta should be null")
         assertTrue(result.tools.isNotEmpty(), "Tools list should not be empty")
 
         val testTool = result.tools.find { it.name == testToolName }
@@ -449,7 +451,8 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val testText = "Hello, world!"
         val arguments = mapOf("text" to testText)
 
-        val result = client.callTool(testToolName, arguments) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        val result = client.callTool(testToolName, arguments)
+        assertNull(actual = result.meta, "CallTool result meta should be null")
 
         val actualContent = result.structuredContent.toString()
         val expectedContent = """
@@ -478,7 +481,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val result = client.callTool(
             complexToolName,
             arguments,
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         val actualContent = result.structuredContent.toString()
         val expectedContent = """
@@ -518,7 +521,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val errorResult = client.callTool(
             errorToolName,
             errorArgs,
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         val actualError = errorResult.structuredContent.toString()
         val expectedError = """
@@ -538,7 +541,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val exceptionResult = client.callTool(
             errorToolName,
             exceptionArgs,
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         assertTrue(exceptionResult.isError ?: false, "isError should be true for exception")
 
@@ -563,7 +566,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val result = client.callTool(
             multiContentToolName,
             arguments,
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         assertEquals(
             2,
@@ -603,7 +606,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val textOnlyResult = client.callTool(
             multiContentToolName,
             textOnlyArgs,
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         assertEquals(
             1,
@@ -645,7 +648,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
                     arguments = arguments,
                 ),
             ),
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         val actualContent = result.structuredContent.toString()
         val expectedContent = """
@@ -671,7 +674,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val result = client.callTool(
             largeToolName,
             arguments,
-        ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        )
 
         val content = result.content.firstOrNull() as TextContent
         assertNotNull(content, "Tool result content should be TextContent")
@@ -692,7 +695,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         val arguments = mapOf("delay" to delay)
 
         val startTime = System.currentTimeMillis()
-        val result = client.callTool(slowToolName, arguments) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        val result = client.callTool(slowToolName, arguments)
         val endTime = System.currentTimeMillis()
 
         val content = result.content.firstOrNull() as? TextContent
@@ -718,7 +721,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
             val result = client.callTool(
                 specialCharsToolName,
                 arguments,
-            ) as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+            )
 
             val content = result.content.firstOrNull() as? TextContent
             assertNotNull(content, "Tool result content should be TextContent")
@@ -802,7 +805,7 @@ abstract class OldSchemaAbstractToolIntegrationTest : OldSchemaKotlinTestBase()
         }
 
         assertNotNull(result, "Tool call result should not be null")
-        val callResult = result as io.modelcontextprotocol.kotlin.sdk.types.CallToolResult
+        val callResult = result
         assertTrue(callResult.isError ?: false, "isError should be true for non-existent tool")
 
         val textContent = callResult.content.firstOrNull { it is TextContent } as? TextContent