Add couple of error_prone rules and fix errors

Improve error_prone coverage of errors.

Test: make cts javac-check -j64 RUN_ERROR_PRONE=true
Bug: 63558780
Change-Id: I062dcc4e28eea0162bf7547dca9bea8d0950d51c
diff --git a/error_prone_rules.mk b/error_prone_rules.mk
index cc28b0d..25d9344 100644
--- a/error_prone_rules.mk
+++ b/error_prone_rules.mk
@@ -16,8 +16,10 @@
 LOCAL_ERROR_PRONE_FLAGS:= -Xep:ArrayToString:ERROR \
                           -Xep:BoxedPrimitiveConstructor:ERROR \
                           -Xep:ConstantField:ERROR \
+                          -Xep:EqualsIncompatibleType:ERROR \
                           -Xep:FormatString:ERROR \
                           -Xep:GetClassOnClass:ERROR \
+                          -Xep:IdentityBinaryExpression:ERROR \
                           -Xep:JUnit3TestNotRun:ERROR \
                           -Xep:JUnitAmbiguousTestClass:ERROR \
                           -Xep:MissingFail:ERROR \