core: support Integer and Long in service configuration parsing

Previously, ManagedChannelImplBuilder and JsonUtil only supported Double
or String for numeric values in service configurations. This caused
IllegalArgumentException when using service configurations produced by
JSON parsers like Jackson that represent non-decimal numbers as
Integer or Long.

This change:
 - Updates ManagedChannelImplBuilder to accept any Number type.
 - Enhances JsonUtil to robustly handle numeric conversions while
   maintaining necessary integral checks.
 - Adds ServiceConfigNumericTypeTest to verify support for Integer,
   Double, and Long types.

Fixes grpc#12815

Author: kannanjgithub

core/src/main/java/io/grpc/internal/JsonUtil.java

@@ -106,8 +106,8 @@ public static Double getNumberAsDouble(Map<String, ?> obj, String key) {
       return null;
     }
     Object value = obj.get(key);
-    if (value instanceof Double) {
-      return (Double) value;
+    if (value instanceof Number) {
+      return ((Number) value).doubleValue();
     }
     if (value instanceof String) {
       try {
@@ -132,8 +132,8 @@ public static Float getNumberAsFloat(Map<String, ?> obj, String key) {
       return null;
     }
     Object value = obj.get(key);
-    if (value instanceof Float) {
-      return (Float) value;
+    if (value instanceof Number) {
+      return ((Number) value).floatValue();
     }
     if (value instanceof String) {
       try {
@@ -159,11 +159,12 @@ public static Integer getNumberAsInteger(Map<String, ?> obj, String key) {
       return null;
     }
     Object value = obj.get(key);
-    if (value instanceof Double) {
-      Double d = (Double) value;
-      int i = d.intValue();
+    if (value instanceof Number) {
+      Number n = (Number) value;
+      double d = n.doubleValue();
+      int i = n.intValue();
       if (i != d) {
-        throw new ClassCastException("Number expected to be integer: " + d);
+        throw new ClassCastException("Number expected to be integer: " + n);
       }
       return i;
     }
@@ -190,11 +191,12 @@ public static Long getNumberAsLong(Map<String, ?> obj, String key) {
       return null;
     }
     Object value = obj.get(key);
-    if (value instanceof Double) {
-      Double d = (Double) value;
-      long l = d.longValue();
+    if (value instanceof Number) {
+      Number n = (Number) value;
+      double d = n.doubleValue();
+      long l = n.longValue();
       if (l != d) {
-        throw new ClassCastException("Number expected to be long: " + d);
+        throw new ClassCastException("Number expected to be long: " + n);
       }
       return l;
     }

core/src/main/java/io/grpc/internal/ManagedChannelImplBuilder.java

@@ -582,7 +582,7 @@ public ManagedChannelImplBuilder defaultServiceConfig(@Nullable Map<String, ?> s
         parsedMap.put(key, checkListEntryTypes((List<?>) value));
       } else if (value instanceof String) {
         parsedMap.put(key, value);
-      } else if (value instanceof Double) {
+      } else if (value instanceof Number) {
         parsedMap.put(key, value);
       } else if (value instanceof Boolean) {
         parsedMap.put(key, value);
@@ -606,7 +606,7 @@ private static List<?> checkListEntryTypes(List<?> list) {
         parsedList.add(checkListEntryTypes((List<?>) value));
       } else if (value instanceof String) {
         parsedList.add(value);
-      } else if (value instanceof Double) {
+      } else if (value instanceof Number) {
         parsedList.add(value);
       } else if (value instanceof Boolean) {
         parsedList.add(value);

core/src/test/java/io/grpc/internal/ManagedChannelImplBuilderTest.java

@@ -737,7 +737,39 @@ public void defaultServiceConfig_intValue() {
     Map<String, Object> config = new HashMap<>();
     config.put("key", 3);
 
-    assertThrows(IllegalArgumentException.class, () -> builder.defaultServiceConfig(config));
+    builder.defaultServiceConfig(config);
+
+    assertThat(builder.defaultServiceConfig).containsExactlyEntriesIn(config);
+  }
+
+  @Test
+  public void defaultServiceConfig_longValue() {
+    Map<String, Object> config = new HashMap<>();
+    config.put("key", 3L);
+
+    builder.defaultServiceConfig(config);
+
+    assertThat(builder.defaultServiceConfig).containsExactlyEntriesIn(config);
+  }
+
+  @Test
+  public void defaultServiceConfig_list_intValue() {
+    Map<String, Object> config = new HashMap<>();
+    config.put("key", Collections.singletonList(3));
+
+    builder.defaultServiceConfig(config);
+
+    assertThat(builder.defaultServiceConfig).containsExactlyEntriesIn(config);
+  }
+
+  @Test
+  public void defaultServiceConfig_list_longValue() {
+    Map<String, Object> config = new HashMap<>();
+    config.put("key", Collections.singletonList(3L));
+
+    builder.defaultServiceConfig(config);
+
+    assertThat(builder.defaultServiceConfig).containsExactlyEntriesIn(config);
   }
 
   @Test