Update string-transformations.md

fixes https://github.com/MicrosoftDocs/azure-docs/issues/48366

Author: yoelhor

articles/active-directory-b2c/string-transformations.md

@@ -9,7 +9,7 @@ manager: celestedg
 ms.service: active-directory
 ms.workload: identity
 ms.topic: reference
-ms.date: 02/05/2020
+ms.date: 02/20/2020
 ms.author: marsma
 ms.subservice: B2C
 ---
@@ -30,7 +30,8 @@ Compare two claims, and throw an exception if they are not equal according to th
 | InputClaim | inputClaim2 | string | Second claim's type, which is to be compared. |
 | InputParameter | stringComparison | string | string comparison, one of the values: Ordinal, OrdinalIgnoreCase. |
 
-The **AssertStringClaimsAreEqual** claims transformation is always executed from a [validation technical profile](validation-technical-profile.md) that is called by a [self-asserted technical profile](self-asserted-technical-profile.md). The **UserMessageIfClaimsTransformationStringsAreNotEqual** self-asserted technical profile metadata controls the error message that is presented to the user.
+The **AssertStringClaimsAreEqual** claims transformation is always executed from a [validation technical profile](validation-technical-profile.md) that is called by a [self-asserted technical profile](self-asserted-technical-profile.md), or a [DisplayConrtol](display-controls.md). The `UserMessageIfClaimsTransformationStringsAreNotEqual` metadata of a self-asserted technical profile controls the error message that is presented to the user.
+
 
 ![AssertStringClaimsAreEqual execution](./media/string-transformations/assert-execution.png)
 
@@ -513,6 +514,42 @@ The following example looks up the domain name in one of the inputParameters col
 - Output claims:
     - **outputClaim**:	c7026f88-4299-4cdb-965d-3f166464b8a9
 
+When `errorOnFailedLookup` input parameter is set to `true`, the **LookupValue** claims transformation is always executed from a [validation technical profile](validation-technical-profile.md) that is called by a [self-asserted technical profile](self-asserted-technical-profile.md), or a [DisplayConrtol](display-controls.md). The `LookupNotFound` metadata of a self-asserted technical profile controls the error message that is presented to the user.
+
+![AssertStringClaimsAreEqual execution](./media/string-transformations/assert-execution.png)
+
+The following example looks up the domain name in one of the inputParameters collections. The claims transformation looks up the domain name in the identifier and returns its value (an application ID), or raises an error message.
+
+```XML
+ <ClaimsTransformation Id="DomainToClientId" TransformationMethod="LookupValue">
+  <InputClaims>
+    <InputClaim ClaimTypeReferenceId="domainName" TransformationClaimType="inputParameterId" />
+  </InputClaims>
+  <InputParameters>
+    <InputParameter Id="contoso.com" DataType="string" Value="13c15f79-8fb1-4e29-a6c9-be0d36ff19f1" />
+    <InputParameter Id="microsoft.com" DataType="string" Value="0213308f-17cb-4398-b97e-01da7bd4804e" />
+    <InputParameter Id="test.com" DataType="string" Value="c7026f88-4299-4cdb-965d-3f166464b8a9" />
+    <InputParameter Id="errorOnFailedLookup" DataType="boolean" Value="true" />
+  </InputParameters>
+  <OutputClaims>
+    <OutputClaim ClaimTypeReferenceId="domainAppId" TransformationClaimType="outputClaim" />
+  </OutputClaims>
+</ClaimsTransformation>
+```
+
+### Example
+
+- Input claims:
+    - **inputParameterId**: live.com
+- Input parameters:
+    - **contoso.com**: 13c15f79-8fb1-4e29-a6c9-be0d36ff19f1
+    - **microsoft.com**: 0213308f-17cb-4398-b97e-01da7bd4804e
+    - **test.com**: c7026f88-4299-4cdb-965d-3f166464b8a9
+    - **errorOnFailedLookup**: false
+- Error:
+    - No match found for the input claim value in the list of input parameter ids and errorOnFailedLookup is true.
+
+
 ## NullClaim
 
 Clean the value of a given claim.