Repository: datadog/dd-sdk-android
Issue: OpenTracing message field gets overridden by default "Span event" message in some cases

**Describe what happened**
In a log event that's attached to a span in a trace, when I set the OpenTracing message field `Fields.MESSAGE` and also set `Fields.EVENT` and `Fields.ERROR_KIND`, the `Fields.MESSAGE` value gets overridden with the default "Span event" message. When I only set `Fields.MESSAGE` and did not set `Fields.EVENT` and `Fields.ERROR_KIND`, the message was properly set.

**Steps to reproduce the issue:**

Message DOES NOT get set with the following:
```java
HashMap propertiesWithOpenTracingInfo = properties.toHashMap();
propertiesWithOpenTracingInfo.put(Fields.EVENT, "error");
propertiesWithOpenTracingInfo.put(Fields.ERROR_KIND, errorKind);
propertiesWithOpenTracingInfo.put(Fields.MESSAGE, message);
span.log(propertiesWithOpenTracingInfo);
```

Message IS correctly set with the following:
```java
HashMap propertiesWithOpenTracingInfo = properties.toHashMap();
propertiesWithOpenTracingInfo.put(Fields.MESSAGE, message);
span.log(propertiesWithOpenTracingInfo);
```

**Describe what you expected:**

On DataDog's website in Log Explorer, the message should be the message that I passed, i.e. `network request error`. But it is replaced with `Span event`, but only when I set other fields, i.e. in order to mark it as an error log.

**Additional context**
 - Android OS version: 11
 - Device Model: Samsung Galaxy S20
 - Datadog SDK version: 1.7.1
 - Versions of any other relevant dependencies (OkHttp, …): 
 - Proguard configuration: 
 - Gradle Plugins:


Changed files:
dd-sdk-android/src/main/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandler.kt
dd-sdk-android/src/test/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandlerTest.kt

diff --git a/dd-sdk-android/src/main/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandler.kt b/dd-sdk-android/src/main/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandler.kt
index a86b81be7..92546ce54 100644
--- a/dd-sdk-android/src/main/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandler.kt
+++ b/dd-sdk-android/src/main/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandler.kt
@@ -85,7 +85,7 @@ internal class AndroidSpanLogsHandler(
 
         if (errorType != null) {
             val stackField = map.remove(Fields.STACK)
-            val msgField = map.remove(Fields.MESSAGE)
+            val msgField = map[Fields.MESSAGE]
             val stack = stackField?.toString() ?: throwable?.loggableStackTrace()
             val message = msgField?.toString() ?: throwable?.message
 
diff --git a/dd-sdk-android/src/test/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandlerTest.kt b/dd-sdk-android/src/test/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandlerTest.kt
index 1df9a3569..40e52dc21 100644
--- a/dd-sdk-android/src/test/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandlerTest.kt
+++ b/dd-sdk-android/src/test/kotlin/com/datadog/android/tracing/internal/handlers/AndroidSpanLogsHandlerTest.kt
@@ -12,7 +12,6 @@ import com.datadog.android.log.LogAttributes
 import com.datadog.android.log.Logger
 import com.datadog.android.utils.forge.Configurator
 import com.datadog.opentracing.DDSpan
-import com.datadog.opentracing.DDSpanContext
 import com.datadog.trace.api.DDTags
 import com.nhaarman.mockitokotlin2.doReturn
 import com.nhaarman.mockitokotlin2.verify
@@ -52,9 +51,6 @@ internal class AndroidSpanLogsHandlerTest {
     @Mock
     lateinit var mockSpan: DDSpan
 
-    @Mock
-    lateinit var mockSpanContext: DDSpanContext
-
     @LongForgery
     var fakeTraceId: Long = 0L
 
@@ -220,7 +216,7 @@ internal class AndroidSpanLogsHandlerTest {
     }
 
     @Test
-    fun `log map with throwable and overriden error fields`(
+    fun `log map with throwable and overridden error fields`(
         forge: Forge,
         @Forgery throwable: Throwable,
         @StringForgery message: String,
@@ -249,7 +245,7 @@ internal class AndroidSpanLogsHandlerTest {
         verify(mockLogger)
             .internalLog(
                 Log.VERBOSE,
-                AndroidSpanLogsHandler.DEFAULT_EVENT_MESSAGE,
+                message,
                 null,
                 logAttributes
             )
@@ -319,7 +315,7 @@ internal class AndroidSpanLogsHandlerTest {
         verify(mockLogger)
             .internalLog(
                 Log.VERBOSE,
-                AndroidSpanLogsHandler.DEFAULT_EVENT_MESSAGE,
+                message,
                 null,
                 logAttributes
             )